Wash Roma tomatoes thoroughly. Dice them into small, even pieces (about 1/4 inch cubes).
In a medium-sized bowl, combine diced tomatoes, chopped fresh basil, minced garlic, and finely diced red onion. Add parmesan cheese if using.
Drizzle olive oil and balsamic glaze over the tomato mixture. Gently toss everything together. Season with salt and pepper to taste.
Cover the bowl and refrigerate for at least 30 minutes to allow flavors to meld. Serve with crusty baguette slices, pita chips, or crackers.