Heat oven to 450° F. Cut the tops off the tomatoes. Scoop out the pulp, roughly chop it, and place in a bowl.
Add minced garlic, red onion, parsley, basil, olive oil, and salt and mix well. Spoon the stuffing into the tomatoes. Place in a lightly greased baking dish.
Bake until the tomatoes are slightly tender, 20 to 25 minutes.