Preheat broiler. Place steak on rack set in broiler pan. Brush top side with the 1 tablespoon soy sauce. Season with black pepper; set aside.
In a small saucepan, stir together the red pepper, oil and garlic powder. Heat on medium for 1 minute. Add peanut butter, rice wine vinegar and the 1 teaspoon soy sauce with 1/2 cup water. Cook until smooth, stirring constantly, for 2 minutes. Keep sauce warm.
Broil steak 3 inches from heat for about 7 minutes. Turn over, brushing with remaining soy sauce and seasoning with black pepper. Broil for 7 minutes more. More time will be needed if you want steak well done. Let stand for 5 minutes before slicing.
To serve, slice thin across the grain. Serve sauce in a small bowl beside meat dish. Serve with peppered vegetables for a complete meal.