1 1/4 lbs. London broil, boneless beef top round steak
Melt 1 Tbsp. margarine in medium saucepan over medium-high heat and cook onion, stirring occasionally, until tender, about 2 minutes. Add tomatoes and salt and cook 1 minute. Stir in Knorr® Bearnaise sauce mix, milk and remaining margarine and bring to a boil, stirring constantly. Reduce heat and simmer, stirring occasionally, 1 minute.