When cutting with a knife, cut with a sawing motion letting the blade do all the work. Do not force down the tomato.
As you cut, use your fingers to hold the tomato in place. Try to cut with a sawing motion, letting the blade do all of the work. This helps prevent you from squishing the tomato down!
Some people don’t bother cutting off the stem, as it’s so small it’s largely unnoticeable. If you don’t mind the tomato stem, you can skip this step.
As Roma tomatoes are smaller than regular tomatoes, be careful when using your fingers to hold the tomato in place. Use only the tips of your fingers and be extra careful to keep your fingers away from the knife.
Strive to keep your cuts the same length so your diced tomatoes are roughly the same size.
Sometimes, seeds linger on the tomato after you cut out of the fleshy portion. If any seeds did not come out, remove them with your fingertips.
