How to get sour cream & onion potato chips flavor?

First things first: If you're trying to precisely replicate the flavor, you'll probably fail. Food scientists put an incredible amount of time, money and effort into developing those flavors and have ingredients and equipment that we don't have access to. Often, the flavors themselves are byproducts of industrial processing, and they've been combined in a way to make them pleasant. So if you're looking to get that exact flavor in your dip, you're going to be disappointed. If you're really just looking for a ballpark approximation which might be a little closer than what you've got now though, you've got a good shot at it.

If I were you, I would first try using dehydrated or freeze-dried green onions or chives which can often be found in glass jars in your grocery store. Mix them with your dip or make them into a powder to toss with your chips. Perhaps pureeing a product like chive cottage cheese which is made with dehydrated/freeze-dried chives might get you there. For the more industrial products, you'll have to look on the internet. Commercial chips almost certainly use sour cream powder (among other flavorants you probably can't find on Amazon) in their sour cream and onion chips. You could even try some sour cream and chives powder to see if that gets you closer, with less work.

Good luck and happy dipping!

I would try adding some softened cream cheese to your dip mixture. Most creamy dips are made up of one or more of sour cream, mayonnaise, and cream cheese. Also, you could try caramelizing the white parts of green onions (or just any old white/yellow onion) for a deeper flavor, and then stirring in the green parts, minced. Don't forget salt (and maybe some pepper) to taste. If that doesn't get you there, garlic powder would be my next choice. Good luck!

Potato chips belong to the most exactly engineered foods we eat. They don't have any taste in themselves, and the flavor on top is created by a complicated industrial process. It is certainly not pure MSG. The exact ingredients and process will be a trade secret of each manufacturer, although there might be a way to look up the main flavor molecules, I don't have such literature at hand. This won't help you further though.

I don't think you have any chance replicating it at home. Maybe you could just dissolve the chips in the dressing and see if the texture stays acceptable for your purposes.

This is not "sour cream & onion" flavour. I can taste only 3 different flavours in chips. For me there are "salt and herbs" "vinegar" and "smoked salt w/ paprika".

Sour Cream and onion is the vinegar taste. It's oniony taste is from sulphur. Like when you mix white vine vinegar with a hint of black salt (not to mistake with baked salt that is black in appearance).

The cheese flavour that you are tasting is the part of "cream". It's Lactic acid. You know, the one you are producing when sweating and then complaining you smells like onions OR sour milk.

So, anyway. If you want to make a dip what you need is sour cream. Sour cream can be bought or made from regular cream by adding either vinegar or citric acid. Then you want to add spring onions. Remember that the white part of onions are more sweet and have "lighter" taste than the green parts. So use that to balance the onion taste and counter acidic of vinegar.

And, if you want to make it taste more oniony just use onion with a sharp taste. Put it in a hot place (or bake it for few second over a fire) and then mince it raw. Or juice it out and use the liquid.

If you taste it later and there will be "not quite this" it will be the umami flavour. Don' be afraid to use MSG to get that or if you want to avoid it use Maggi or few drops of soy sauce.