Drizzle the bottom of a dutch oven with olive oil. Once it heats up, put in the diced onions and sauté until soft (about 5 min). Put in the garlic and sweat until fragrant, being careful not to burn (about 30 seconds). Add the the San Marzano tomatoes, crushing by hand or with kitchen utensil. Add the tomato puree, sauce, tomato paste and water. Stir with wooden spoon until smooth.