How do I sautee tomatoes without them being juicy?

When tomatoes are used as a vegetable in a dish that does need extra water, I will often de-seed my tomatoes. For example, when I put them in an omelet.

The process is simple. Just cut the tomato in half and sweep and the seeds and pulp. Use the remaining flesh as a vegetable.

This technique will work with any tomato but obviously some are better suited for it than others. The meatier the tomato the more will be left. Juicy delicate tomatoes won't have much flesh remaining.

Another tradeoff is that the bulk of the fresh, tomato flavor is found in the juicy pulp that is being discarded. I've tried to boil off the water and put the resulting "sauce" back in but I found it wasn't worth the effort.

In addition to what's already been mentioned, try salting or brining them (any kind of tomato), before draining them. That will cause them to release more water and become more concentrated in flavor. See also Keeping scrambled eggs with tomatoes from being too watery.

First off, tomato paste is sometimes helpful but definitely not essential for making a tomato sauce; see this answer in another thread.

In my experience, grape tomatoes tend to have a pretty high ratio of internal goo around the seeds, within what is technically called the locular cavity (who knew?) This stuff has very little in the way of structure and tends to break down into a watery mess when cooked. Fortunately, switching to Roma tomatoes will help with this; they and other plum tomatoes have less of this stuff since they're intended primarily for sauce applications. Less goo equals less moisture starting off.

My first instinct to address extra juice would simply be to pour or strain it off. If you strain over a work bowl or vessel of some kind, you could easily add it back to your own preference.

You could also try dehydrating the tomatoes in a low oven first to drive off some of their moisture, then finishing them in the pan. This does of course cook them somewhat, so you'll need to back off on your saute. Alternatively, you may even find that roasting the tomatoes without any saute at all produces a similar result with a deeper flavor. You will lose some of that "fresh" flavor that you're keeping by giving the tomatoes a quick saute, but it all depends on what you're going for.

Besides the comments that have been mentioned in preparing the tomatoes before cooking (I highly suggest pulling out the seeds & jelly like substance around them, as Sobachatina mentioned):

I find that high heat, so you just cook the outside, without breaking down the middle of the chunks of tomato also helps.

The high heat will also help to boil/reduce any juices that come out, but you have to use the proper sized vessel for the amount of tomato -- too large a pan with too much heat might get some burning, while too small of a pan will cause the tomatoes to be steamed, as the moisture can't escape quickly.