The Simplest Tomato Sauce

1 (28 oz.) can whole peeled tomatoes, w/juices

1 onion, peeled and halved

5 Tbsp. unsalted butter

salt, to taste

Combine tomatoes, onion and butter in med. saucepan over med. heat.  Bring mix to a simmer, then reduce heat to keep sauce at low, steady simmer for 45 min.  Stir occasionally, crushing tomatoes against side of pot w/wooden spoon.  Remove from heat, discard onion, add salt to taste.