1 package Knorr® Rice Sides™ - Chicken flavor, prepared according to package directions
Season steak, if desired, with salt and ground black pepper. In 12-inch nonstick skillet, heat 1 Tbsp. margarine over medium-high heat and cook steak until desired doneness. Remove steak and keep warm.
In same skillet, heat remaining 3 Tbsp. margarine over medium-high heat and cook red pepper and onion, stirring occasionally, until vegetables are tender, about 5 minutes. Add vinegar and cook 1 minute. To serve, slice steak and arrange over Knorr® Rice Sides™ - Chicken flavor, then top with red pepper mixture.