Bring a large stockpot to boil. Add a healthy amount of kosher salt right before adding the pasta. If using tortellini, either cook in a separate pan or add a few minutes later so that all the pasta ends up cooking at the same time.
Boil according to the package directions, checking it around 2 minutes before it's expected to be done.
Drain the pasta in a colander and set aside till cool.
Once the pasta is cool, add half of it to a large wide serving bowl along with half of the chopped tomatoes and cheese. Toss lightly and then add the remaining pasta, tomatoes and cheese.