Sauté onion slices in hot oil in medium-sized saucepan.
Process canned tomatoes in blender or food processor with garlic; strain. Add tomatoes and garlic to sautéed onion slices. Season with
salt and pepper and add oregano. Add sugar and correct seasoning.
Cover and cook over medium heat for 5 minutes. If sauce thickens
too much, add chicken broth or tomato juice and cook 2 minutes longer.
Take to the table in a sauceboat or serve over Chiles
Rellenos to cover.
Adapted from "Mexican Family Cooking"