I saw this quick homemade tomato sauce made on America's Test Kitchen before I started regularly recording the show . . . I tried to find the recipe online and opted out of the "joining" thing. Lo and behold my May/June Cook's Illustrated features the recipe.
2 T. unsalted butter
1/4 cup grated onion from 1 medium onion
1/4 t. dried oregano
2 medium garlic cloves, minced or pressed through a garlic press (about 2 teaspoons)
1 28 oz. can crushed tomatoes
1/4 t. sugar
2 T. coarsely chopped fresh basil leaves
1 T. extra vigin olive oil
Ground black pepper
Heat butter in medium saucepan over medium heat until melted. Add onion, oregano and 1/2 t. salt; cook, stirring occasionally, until liquid has evaporated and onion is golden brown, about 5 minutes. Add garlic and cook until fragrant, about 30 seconds. Stir in tomatoes and sugar; increase heat to high and bring to simmer. Lower heat to medium low and simmer until thickened slightly, about 10 minutes. Off heat, stir in basil and oil; season with salt and pepper. Serve.
Preferred brands of crushed tomatoes are Tuttorosso and Muir Glen. Grate the onion on the large holes of a box grater.