Keeping scrambled eggs with tomatoes from being too watery

Another effective method (not mentioned in the link SAJ14SAJ provided) is salting. Dice the tomatoes, generously salt them and leave them in a sieve for 20 minutes or so. You probably want to squeeze off some of the juicy bits first. Flip the tomatoes half-way through the resting time. That will draw off a lot of water without pre-cooking the tomatoes (which will also work, but will change (not necessarily negatively) the taste of the tomatoes. If you use kosher or other coarse salt, you'll be able to shake or wipe off quite a bit of the salt before proceeding with your application.

When I have very fresh and very ripe tomatoes, I don't like to cook them as their structure breaks down with heat and quickly becomes grainy. Another option in addition to others' wonderful recommendations is just to prep the tomatoes separately. Peel them by blanching and shocking them so the skin comes apart, split, and scoop out the seeds. Dice, and add chopped fresh tomato to the omelette at the very end of cooking.

Usually I will fry my tomatoes alone on high heat before making the omelette - if you cut each tomato into eighths and fry them facedown for a minute then flip for another minute, the outside is seared and some of the internal water will have cooked off.

I suggest effectively partially sun drying them by putting them in a very low oven for a very long time.

From a horticultural point of view, the breed of tomato you're using will make a difference. There is one by Nunhems called 'Intense (tm)' - this one was developed specifically for professional sandwich makers, because they have fewer pips and pulp, and so don't make the bread soggy. You might find that using the right variety of tomato helps, though I imagine even 'Intense' will produce moisture when cooked.

In my experience, the seedier the tomato, the more juice it produces, so I agree with "horticulture guy". What I do is simply cut away the seed portion of the tomato and use the rest, adding it as late as possible in the recipe. When using tomatoes in my omelets I frequently sprinkle the diced tomato on the very top just prior to removing it from the pan. Delicious, and it makes a pretty presentation on the plate.

Here's my solution. First, it helps to use a firm tomato. After I dice them, I put them in a paper towel and squeeze as much water out of them as I can, over the sink, and then add them to the egg mixture. The end result might look a little weird, but the flavor is all there, and most importantly there is no excess water. This method is fast, it's easy, and it has never failed me.

The two main ways you can remove as much moisture as possible (you'll never get rid of all of it) is: 1. salting, either before you throw it into the pan to drain as much liquid as possible and/or while you pan fry it dust salt over it (to taste) and let the pan's heat evaporate the water 2. removing the seeds as much as you can. either cut the tomato in half and scoop out or blanch and scoop.

If you don't like these solutions, Kiwis have a great way of baking tomatoes in the oven (slice in halves and put the cut side up on a baking sheet) with some salt and pepper. You could top with cheese if you want them to be extra indulgent. Even though it's an extra step, it removes a lot of the water and you can still eat them with the scrambled eggs on the side.