Line your baking sheet with aluminum foil, spray it with nonstick cooking spray, and set it aside. Preheat the oven to 450℉/232℃.
Prepare your tomatoes by rinsing them with cool tap water, then pat dry with a paper towel. Cut tomatoes lengthwise in half, and remove as many seeds as desired. A spoon helps with this process. Set aside.
Combine the olive oil, minced garlic, Italian seasoning, fresh basil, balsamic vinegar, salt, and pepper in a large bowl. Mix to thoroughly combine. Add halved tomatoes to the bowl and gently toss to cover each piece well.
Transfer the tomato halves to the prepared sheet with the sliced side up, then drizzle 1-2 tablespoons of the remaining oil mixture over them.
Oven-roast the tomatoes until they are charred, 40-45 minutes. Allow roasted tomatoes to cool before using or dice them, and then store them in the fridge or freezer in an airtight container.