Heat oven to 450º F. Cut the tops off 4 tomatoes. Scoop out the pulp, roughly chop it, and place in a bowl. Add 2 minced garlic cloves, 1/2 cup chopped red onion, 1/3 cup chopped fresh parsley leaves, 1/4 cup thinly sliced fresh basil leaves, 2 tablespoons olive oil, and 1 teaspoon 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.