1 28-ounce can whole peeled tomatoes, or 2 pounds fresh tomatoes, peeled  and cored
5 tablespoons unsalted butter
1 medium yellow onion, peeled and halved
Salt, to taste
Chiffonade  of basil (optional)
- Place the tomatoes, butter, and halved onion in a medium saucepan (3 quarts or larger).
- Bring the sauce to a boil, then lower the heat to a simmer, and cook for 45 minutes, or until the butter droplets separate from the tomato juices. Discard the onions.
- Using an immersion blender, pulse a few times to break up large chunks of tomato. Alternatively, run the sauce through a food mill , on the coarsest setting. Season to taste if necessary.
Serves 4-6; makes enough sauce to dress 1 pound pasta.
- Save the tomato-braised onion halves to serve finely chopped as an accompaniment to sausage.
- While perhaps best in its most elemental state, glossed over strands of spaghetti, it could be slathered on pizza , layered in lasagna, or employed as a poaching liquid for eggs .
- Condiments/Sauces, Other