Sprinkle beef with seasoned salt and pepper. Alternately thread beef, bell peppers and onion onto six 12" to 14" metal skewers. Brush beef and vegetables with oil. Grill over medium heat until beef is of desired doneness, turning once.

 

During last 3 to 5 minutes of grilling, place buns, cut sides down, on grill. Cook until toasted. Spread with mustard-mayonnaise sauce. Top bottoms of buns with cheese.

 

To serve, place kabob over cheese in each bun; carefully remove skewer, holding bun firmly around beef and vegetables.