Make the vinaigrette first. Add the olive oil, balsamic vinegar, Dijon mustard, minced garlic, salt, and pepper to a bowl, then whisk until smooth.

Finely dice the tomatoes. Add the tomatoes to a large bowl, then pour the dressing over top. Stir the combine the tomatoes and dressing, then set them aside to marinate.

Cook the penne pasta according to the package directions (boil 7-8 minutes, or until tender), then drain well in a colander. Allow the pasta to cool.

While the pasta is cooling, roughly chop the basil.

Give the tomatoes another stir, then add the drained and cooled pasta and chopped basil to the bowl. Stir until everything is evenly combined and coated in dressing. Taste the pasta and add more salt or pepper if needed. Serve immediately or refrigerate until ready to eat.