Warm the oil: Set a medium pot over medium heat.
Add olive oil and let it shimmer.
Sweat the aromatics: Add the chopped onion with a pinch of salt. Cook 6–8 minutes, stirring, until soft and translucent, not browned. Add the garlic and cook 30–60 seconds, just until fragrant.
Build the base: Stir in tomato paste and cook 1–2 minutes to caramelize slightly.
It should darken a shade and smell sweet.
Deglaze: Pour in the red wine. Scrape up any bits from the bottom and let it reduce by about half, 2–3 minutes. If skipping wine, add a splash of water or broth instead.
Add tomatoes and seasonings: Stir in crushed tomatoes, dried oregano, dried basil, red pepper flakes, bay leaf, and the Parmesan rind if using.
Add 1/2 teaspoon salt to start.
Simmer gently: Bring to a gentle bubble, then reduce heat to low. Partially cover and simmer 30–45 minutes, stirring occasionally. The sauce should thicken slightly and taste richer over time.
Balance and finish: Taste.
If the sauce is too sharp, stir in 1/2 to 1 teaspoon sugar. Add the butter for a silky finish. Adjust salt and pepper.
Fresh lift: Remove bay leaf (and Parmesan rind).
Stir in torn fresh basil right before serving for brightness.
Pair with pasta: Reserve a splash of pasta cooking water. Toss the sauce with hot pasta, adding a bit of the starchy water to help it cling. Serve with grated Parmesan.