Heat olive oil over medium heat. Add onion and cook 5–6 minutes until soft. Add garlic and cook 60 seconds.
Add crushed tomatoes, oregano, red pepper flakes, salt, and pepper. Stir to combine.
Simmer uncovered on medium-low for 18–20 minutes until thickened and glossy.
Taste and adjust — add sugar if too acidic. Stir in fresh basil and pasta water. Toss with pasta and serve.
Notes
- Add fresh basil at the very end — adding it early kills the fragrance. - Reserve pasta water before draining — the starch binds sauce to pasta perfectly. - Freezes well for up to 3 months — make a double batch every time.
Keyword classic tomato pasta sauce, homemade tomato sauce, san marzano pasta sauce