Combine all ingredients in a medium saucepan over medium-high heat. Bring to a boil, then reduce the heat to a simmer. Allow to cook for at least 15 minutes. Once finished cooking, remove from the heat. If you prefer a smoother sauce, use a potato masher or immersion blender to break up the chunks of tomato. Alternatively, simply leave it as is if you prefer a chunkier sauce. Store in an air-tight container in the refrigerator.