Slice beef against grain into 1/4" slice (2 or 3 inches long). In bowl, stir together sugar, soy sauce, oil, sesame seeds, green tomatoes, garlic and black pepper. Add meat. Toss until all pieces are coated. Cover and marinate 1 to 2 hours at room temperature or 4 or more hours in refrigerator. Place strips 1" apart on racks then broil or barbecue 1 minute on each side. Serve immediately garnished with green pepper slices.