Learning how to make marinara sauce from scratch is easier than you might think. In our recipe, slow roasting concentrates the flavor in the tomatoes, making for a much heartier and somewhat thicker sauce. You can freeze the sauce in pint containers for up to six months. If you don't have a food mill, puree the sauce in a blender or food processor and strain through a sieve.
Roast seasoned tomato halves, cut sides up, at 250° for 7 hours. If you don't have the time—instead of slow roasting, you can blast the tomatoes at 450° for 20 minutes or until they begin to brown. The sauce will be slightly thinner but still vibrantly flavored.