- 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. Remove the onions and reserve for another use.
- 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.
- Other, Condiments/Sauces
- Serves 4-6; makes enough sauce to dress 1 pound pasta