Fastest way to peel and dice vegetables?

...a sharp knife and practice...seriously. First, there are a couple of types of peelers. I prefer a Y peeler for most situations because, for me, I find it more maneuverable. Peeling time is really quite minimal, unless you are prepping for a crowd. Knife skills are probably more important, but you have to build up speed and efficiency given the need to be safe. These knife skills begin with good, quality tools, which you must maintain to keep sharp. You then need to learn safe and efficient ways to prep various items. Over time, you will get faster. There is nothing creative about it. All those "fancy" devices and tools just slow down someone who is efficient with a knife, because they have to be put together, taken apart, cleaned...etc.

As I am following a whole-food plant-based vegan diet, the amount of vegatables I cut is considerably larger than for the "average" home cook. In addition to tools and techniques discussed in the other answers, here is what I have learned:

• Get a large cutting board. It avoids wasting time with moving things around on the board, things falling off on the sides, or picking things from the floor and re-washing them.
• Use a bowl or plate to collect peels and other pieces that are cut off, this speeds up cleanup.
• Bulk-wash all vegetables for the recipe, then bulk-cut.
• Do not peel everything. Often most nutrients are in the peel, for example in in potatoes. Eating potatos with peel is quite common, for example in Scandinavia. This means better washing is required so there is a time trade-off. Furthermore, I would recommend this only when organic produce is used.

The answer to the question what the fastest way is, entirely depends on the volume you are preparing. Because using some kind of specialized devices will usually require some additional time to set them up and clean them afterwards.

• So for small amounts there probably is no faster way than using a simple knife and some training.

• For slicing or dicing medium amounts of vegetables using a mandoline could be a good choice. If you are looking for robust premium quality check the models of Bron Cuocke or De Buyer.
  There are also non-flimsy versions of the manually operated gadgets you used available e.g. for cutting french fries or slicing tomatoes, but imho they are too expensive and not versatile enough to be a usefull investment in a home kitchen.

• And if you are preparing large or huge quantities regularly there are also professional grade, electrical powered machines like potato peelers (aka potato rumblers) or vegebable slicers available that can process several kilos in a single batch.

Other people have already mentioned peelers and sharp knives, but you also asked how to improve your knife skills.

If you’re near a decent sized city, there is likely a place that gives cooking lessons, and most of those will also have classes on knife skills. You can search online, or ask at kitchenware stores.

You can also try watching videos online, and you will likely learn things and improve, but a real teacher will be able to watch you and correct any mistakes that you might be making.

I'm not exactly answering your question, but I think this will be more useful:

To speed up your cooking, you don't primarily optimize the way you execute a recipe. Rather you optimize the recipe.

In particular when it comes to peeling, you can skip that for a lot of plants: Potatoes, sweet potatoes, carrots, beetroot, for example, can all be eaten whole without peeling (and by the way if you can't wash off small amounts of dirt or if there are little blemishes on the outside, you still can eat that just fine). Sometimes this means you need to be a little creative with the way you cut up the vegetables - large pieces of skin can negatively change the mouthfeel, small pieces usually don't.

For dicing, depending on the amount, a simple knife or more and more elaborate tools can be the way to go - but do you really need pretty dices? Maybe you can think of another way to cut up the vegetables while still resulting in a tasty end result: Chopping, or shredding with the aid of a tool, or maybe leave it in larger pieces.

You know those old-timey TV scenes of people sitting out on the front porch peeling spuds and shelling peas? You, too, can go sit somewhere else while peeling. Like in your living room, with whatever media you prefer to casually consume (audiobook, podcast, recorded lecture, movie or TV that you don't have to watch 100%). You can use buckets or whatever to keep stuff clean, but traditionally a plastic "dish pan" is just right--one in your lap for unpeeled and all the peels, one beside you (sometimes with water in it, depending on the veg) to put the peeled stuff in as you peel. This doesn't actually make peeling faster, technically, but it does make it feel a lot faster and if you were going to watch/listen to whatever it was anyway then the time is "free".

Peel and chop in larger batches, whenever you can store the excess for future use. You'll have to look up what storage method is best for different types of veg, but doing a big batch assembly line style (peel everything, chop everything, etc.) is much faster per quantity than doing small to medium amounts every time. (Some things will even store cooked, for example you can make a much larger batch of soup and store the soup.) Also, that way you get to listen to a full episode.

I've used both Y and straight(?) peelers for years, I do not think it matters which you use. What is important is how well you use it, and ultimately this comes down to practice. Constantly re-evaluate how you peel, and whether this is more/less efficient. Obviously for really hard-skins, these sorts of peelers are pretty useless.

One way to speed this up, is when selecting vegetables that you would normally peel, only buy ones that will peel easily. A good example of this is sweet potatoes. Often these come with all sorts of tangles & turns, which exacerbate the peeling time. But you can pick & choose, only buying ones with relatively straight sides, leaving the lumpy & bumpy ones to people who enjoy the challenge ;)

Sometimes I do not peel pumpkin (before baking), but I do wash the outside, giving it a vigourous scouring with a stainless-steel ball-pad-thing. This removes all of the crusty skin parts, and softens the rest. Perhaps you could try this with other veg. It may be enough to simply scour them a bit during washing. However I sometimes find skins (potato, carrot) to have a quite strong, diagreeable flavour. No-one else in my family tastes this, just my mum & me.

The equipment that you place a piece of veggie in and pull down an arm to dice works wonders. But yes, most all such consumer devices are garbage. Either they flop apart, not from mis-use, but rather just from slightly-not-precisely-right use.

But they work wonders. So go online looking for restaurant equipment suppliers. A number of them so you can weed out the posers who are still selling consumer junk to consumers pretending it's restaurant grade.

Or go to your local Golden Corral or other buffet and just ask "What brand is that beast over there that you just put two heads of lettuce into and in a couple seconds had chopped lettuce?" Then look for that brand, and presumably, its smaller siblings.

Real restaurant equipment will often (close to always) cost more (different economics) but usually is not touchy about imprecise use and will often clean rather easily. Bear in mind though that peeling equipment (the kind that you pour potatoes into, say, close it up, and it rotates, peeling the potatoes as they move around the sidewalls) uses a flow of water, plenty of it for a home kitchen, and it has to go somewhere. With solid matter in it.

If using hand tools, as mentioned, a very sharp knife that is kept sharp is a safety item. Well, IF, and it's a big if, you handle it properly which includes CAREFULLY. The reason a dull knife is dangerous is you lose that care and technique as you fight to get it to do anything you've learned to do. And the fact that a "dull" knife means it cuts a quarter inch into your finger before you stop giving you a ragged shred of finger hanging about that takes an ER to fix rather than it cuts swiftly and cleanly down and out the end of your finger before you stop it and that takes an ER to fix.

Peelers are the same. One answer noted you can have one of those Y-peelers shave a fingernail when peeling out and away. Um... as opposed to shaving the base of your thumb if you peel toward yourself? Nothing is safe if you exceed the speed that you, YOURSELF, are currently safe at.

Both knifework and peeling are very much dependent upon the person, not one technique or tool being better than another. And they aren't, neither techniques, nor tools. I simply cannot, cannot, peel toward myself. I have no decent control, no speed, and I tend to not peel, but rather dig in somewhat, which ends up the same as if using a dull peeler: I lose the big, safe and efficient, picture, and pull harder causing it to leap out. Others I've talked to find it the opposite. They have no control at all unless peeling toward themselves. Same kind of thing with knifelike peelers vs. the Y kind. (I know no one though who is comfortable though with the knifelike peelers whose handles are taller than they are wide.)

Remember that catching thing though, for peeling. There are lots of ways to have a peeler catch and if you deal with them properly, peeling can be FAST and smooth, your speed ramped up appreciably without major work. Anything sticking up from the surface (blemishes on anything, sprouting eyes on potatoes, and so on) catches the peeler and trouble ensues. Remove them immediately. Do not remove developing eyes until after peeling. They're easier then, and you'll spot some that haven't affected the surface. But mostly, the edges of the holes that removing them creates catch your blade. Keep a good paring knife handy because not every blemish is best dealt with by the peeler. Another piece of safety is that you never touch anything wet with your peeling hand. Keep water running to constantly rinse your holding hand. (Not hard! Just enough to rinse a hand, and also the potato... some blemishes turn out to be particulate matter instead.)

For knifework, use the same safety ideas. If it feels more right to you to cut away from you instead of the common point down, rock down and cut like closing a garlic press so the cut finishes nearest to you, then do that instead. Learn to at least move your fingers while the knife is anchoring the food while finishing its cut if you find you can't attain a more optimal feed using the fingertips. The rate at which you move your fingers back on the item correlates EXACTLY with the length of the cut pieces if you develop the usually taught techniques. So rather than "Stop, look, and listen" before each cut, you can begin to get a flow of activity going on.

Most people, not me, but most, like every bit of veggie to feel the same when eating. So the "cut same size pieces" idea is important to learn. It DOES mean you have to toss out parts that can't fit the chosen size. "Toss out" as in "Can't use them in this meal" not "Into the trash." Keep a container, Glad bags work nicely but so does Tupperware, in the FREEZER for all such as well as peelings you are good with keeping. They flavor stock most nicely and even the peelings will contribute nutrients. Bear in mind veggies lose nutritional value due to their nutritive elements being destroyed by the cooking process and peeled or not, a great deal of loss occurs just because you cooked the veggies. Don't keep peelings because you imagine all those nutrients being thrown away. They would have largely been lost anyway. But if you wish to keep peelings, do make sure to remove anything you can't abide before peeling, so they are easy to use in stock, say. You do not want to have to carefully examine each frozen peeling for usefulness! Washing well, with soap if you think they have oil-based poison on them (meant to keep it on them through thunderstorms, so not removed by dipping them in holy water) or if organic, the liquidified animal feces sprayed on them as fertilizer. Yum, organic... so much better. Wash in soapy water and rinse under hot running water, then leave in a sizeable tub of hot, clean water that you change. Not helping to speed up your cutting them, I agree, but what's the point if you are going to eat nerve poisons or chicken and pig feces? (That's right... you don't think Tyson is paying to dispose of that when they can sell it instead do you? Yum, it's organic!)

I'm strong on the "you have to do it how it works for you on a basic level, then improve to where you can with that basis" thing. But here's the thing: for some people none of that works at all. They try, they do, but the knife just wobbles and flops around, their best efforts at methodical cutting (not even finger-feeding, just... being methodical) don't pan out at all. A mess of all kind of chunks. For them, just basic chopping is very hard and barely, or doesn't even, happen. You can see plenty of this on YouTube. They are earnest, have some idea, often anyway, of what to do, but don't come close at all. Their minds don't coordinate the details on this subject properly. It's that, not some general incompetence or willingness to be 2,734th best.

In truth though, they are just the most obvious "never will be able to go past a certain point" folks. The rest of us are in between and live with the illusion, usually, that it just takes work to get better. Or a piece of knowledge we just don't have. The actual truth is that we all need to examine the difference between what we do naturally while aware of how really skilled people do it, and our attempts to do it like they teach. Finger-feeding just isn't any more natural to me than peeling toward me. I understand it, I can do it for brief periods, but I do not adapt as a little bump here, a little stickiness due to a potato shedding water and starch there, as life occurs and I break from it into a slow version of it that is really more of a "look at the piece I'll cut if I don't move my fingers more, or go back a little, and can I live with that... CUT, repeat" even though all the taught elements are there. I touch type, but always while watching my output. Even in typing class in 1978, I read a bit of the material, touch typed (mostly), always watching the output. That's really exactly what I do when chopping veggies. It's obviously a basic aspect of my nature, not some habit of cutting that I just need to break. It's the same for all of us.

Find which techniques directly feel right. Do them. Bear in mind the goals you have and all the techniques you know for achieving them. As you use your natural approach, try to find workable ways to bring those goals and speed helps to advantage in your approach. You aren't going to have to chop the veggies for 85 covers in the next hour or be fired. YOU are the boss. And if, over time, some of the techniques you learn, but have a hard time applying start to become easier, run with that (with that, not with the knife, peeler, or scissors). But always remember you cannot be like Barry Bonds by using his HGH and batting techniques. You can just apply what you can to yourself and use them, when you can (his techniques, not the HGH), to make your own technique closer to the best it can be. Being 90% of what YOU can be is your goal, not being 10-20% of what some TV chef is. As corny as that sounds, it's the truth.

Lastly, consider, for potatoes, those "Rotato Potato" type tools. They are much faster than even a decent home cook at peeling, and so long as you do useful things like let the peeling fall into a sink rather than pile up, move their parts carefully (not "slowly"... "carefully"), and always buy the stainless steel blades for them, they work amazingly well. They are so similar — plainly there's one OEM somewhere in China — that brand doesn't matter much. Very safe if your not silly.

Speaking of silly: when you buy a peeler, it will come with a blade guard so cheap packaging can be used in stores where kids can take them off the hook... So many people throw those away. DON'T. Treasure them. Always keep peeling and removing eyes and such separate tasks and put the silly blade guard on the peeler any time you are not directly peeling!

And if using a mandolin, do buy one of those chainmail gloves. You can't have speed with them and be safe without one. Also, no matter which one you buy, it has to be solid and STAY PUT as you use it. Handy with tools? Build a base for its feet. If not, then place something like a cutting board between the end that will move as you slice something down across it and something solid, like wall or a toaster, whatever, just something so it will not move in the blade's direction of travel. Press down some, but keep most your force in line with the slice across the blade, not down! Always move your hand that direction only. This is a follow through kind of thing, like a golf or bat swing. That continued motion after the item has cut completely doesn't help it be cut better. But it helps make sure the part of the motion that did matter was done right, that it did not stop being right 90% of the way through, then go awry. "Awry" is when fingertips or base of thumb flesh get slice along with the veggies.

My 2¢ regarding fast peeling.

I use a 'Y' peeler, as mentioned in one of the answers above, but the thing that makes my peeling faster is holding the vegetable inside a thick towel, which is also long enough to completely cover my wrists etc.

This makes the cutting safe (because in the unlikely scenario the peeler slips, it will land on the thick towel instead of my wrist), and therefore this speeds the whole process considerably, as you do not have to peel slowly and carefully to avoid injury.