Heat Oil In A Large Frying Pan Set Over Medium-High Heat. Saute Onions And Green Pepper For 5 Minutes. Add Beef To The Pan. Cook, Stirring Until Browned, About 5 To 10 Minutes. Drain Off Fat. Stir In Ketchup, Worcestershire Sauce, Sugar, Salt And Pepper. Simmer Over Medium-Low Heat, Stirring Occasionally, For 10 Minutes Or Until Slightly Thickened. Serve On Sandwich Buns.