Learn How to Seed Tomatoes for those times when tomatoes without seeds are just what the recipe ordered. It's a simple technique that can make slicing and dicing much easier while reducing the overall water content from tomatoes.
Cut the tomato through the stem into 4 wedge-shaped slices.
Using a sharp paring knife, run the blade under each pocket of seeds, along the inner flesh of the tomato itself. The seeds and gel should release as you cut.
Discard the seeds (or reserve for another use). If your recipe calls for slices or dices, slice each piece into strips about 1/2-inch wide.
Working in batches if needed, line up several strips and cut them cross-wise into small, tight diced pieces. Move the diced tomatoes into a bowl as you work.
Notes
Make sure your knife or knives are in tip-top shape and very sharp. Because they’re so fragile, the best knife for tomatoes is often a narrow serrated knife. A paring knife comes in handy, too, if you need to cut out the core of the tomato.
Double-check the recipe you’re using. Do you also need to peel the tomatoes? If so, see my tutorial on how to peel a tomato. It’s easier if you peel first, before seeding.