• Place tomatoes, onion, and halved garlic in a foil-lined roasting pan. Drizzle or spray with extra-virgin olive oil. Sprinkle with kosher salt and black pepper. Place the pan in a preheated oven at 400°F and roast the tomatoes for 1 hour. Flip peppers halfway through.
• Once cool, peel garlic cloves and transfer along with tomatoes, onion, peppers, and pan liquids to a Vitamix blender and puree until smooth.
• If you don't have a Vitamix blender, remove tomato skins, then add them to a Dutch oven with the other roasted veggies. Use an immersion blender to blend the sauce, either chunky or smooth.
• Add crushed red pepper flakes, dried or fresh herbs, and balsamic vinegar. Taste and adjust the seasoning, if needed. You can optionally add a teaspoon or two of brown sugar or a few tablespoons of red wine to balance the sauce's flavor. Simmer for 15 minutes.

Optional

• If you don't plan on waterbath canning the sauce, add ½ teaspoon of baking soda. This raises the PH balance of the sauce, making it less acidic. However, it can make the sauce unsafe for canning. Instead, add the baking soda when you are ready to consume the sauce.