If using fresh tomatoes, score the bottoms and blanch in boiling water for 30 seconds, then plunge into ice water. Peel, core, and crush by hand; if using canned San Marzano tomatoes, simply crush them in a bowl.

Heat olive oil in a heavy pot over medium. Add chopped onion, carrot, and celery, cooking for 6–8 minutes until softened and golden.

Stir in minced garlic and cook for 30–45 seconds until fragrant, taking care not to let it brown and turn bitter.

Add tomato paste and cook for 1–2 minutes, stirring constantly to caramelize and deepen the sauce’s umami flavor.

Pour in crushed tomatoes, then stir in oregano, dried basil, red pepper flakes, sugar, salt, and pepper until well blended.

Bring to a low boil, then reduce heat to a gentle simmer. Cook uncovered for 45–60 minutes, stirring every 10 minutes, until thickened.

If the sauce is too thin, simmer longer; if too thick, stir in a splash of water. Taste and adjust seasoning as needed.

Remove from heat and stir in chopped fresh basil. Cover and let rest for 10 minutes to allow flavors to marry.

Use immediately over your favorite pasta or let cool completely before transferring to storage containers for refrigeration or freezing.