Meanwhile, in a large saucepan, heat 3 Tbsp. olive oil and add onion and garlic. Saute for about 5 minutes until the onion begins to brown. Add red wine (if using) and simmer to reduce for 1 -2 minutes. Add the tomatoes, turn down the heat to a gentle simmer, partially cover, and let simmer for about 1 hour. Stir occasionally. If the sauce is sticking to the pan or getting too thick, add some water, 1 Tbsp. at a time.