Combine the tomatoes, garlic, salt, pepper, sugar, olive oil, and balsamic in a large bowl. Stir to mix well and allow the tomatoes to marinate at room temperature for at least 1 hour, and up to 6 hours before making the pasta salad.
Make the Pasta Salad
When the tomatoes are ready, set a medium pot with plenty of water over high heat. Add a tablespoon of salt to the water, then cook the pasta according to the package directions. Drain the pasta.
Add the still warm pasta to the bowl with the tomatoes and all of their juices. Toss thoroughly until everything is well-coated. Add the parsley and toss again. Taste the pasta, then add salt and pepper to taste.
Serve immediately, or cover and refrigerate until ready to eat. Stir again before serving. Just before serving, sprinkle Parmesan over the top, if desired.
Notes
I’ve marinated just about every possible variety of tomatoes with this recipe. It will work nicely with whichever tomatoes you happen to have on hand.