Heat the olive oil in a large pan over medium heat.
Add the diced onion and sauté for 3 to 4 minutes, or until softened. Stir in the garlic and cook for an additional 30 seconds.
Incorporate the San Marzano tomatoes, along with their juices, oregano, red pepper flakes (if desired), salt, pepper, fresh basil, and a quarter cup of water.
Stir the mixture thoroughly and bring to a simmer. Lower the heat and continue to cook for about 20 minutes, or until the sauce has thickened. Adjust the seasoning with additional salt and pepper, if necessary.
Remove and discard the basil sprigs. The resulting sauce will be chunky. For a smoother consistency, blend some or all of the sauce in a blender. Serve immediately or refrigerate for up to four days.
Notes
For optimal flavor, choose high-quality extra virgin olive oil and Italian canned tomatoes. San Marzano tomatoes, known for their unique sweetness and texture, are highly recommended. Look for tomatoes with the “D.O.P.” label, which ensures authenticity.
This sauce remains fresh in the refrigerator for up to four days and can be frozen for up to two months. Thaw frozen sauce in the refrigerator overnight and reheat it on the stove until warmed through.