2 - Tablespoon butter or margarine
1 - onion, sliced
1 - green bell pepper, cut into thin strips
2 - package (6 ounces) deli select roast beef, cut into thin strips
4 - submarine rolls or hoagie rolls, cut into halves
1/2 - pound Provolone cheese, sliced

• In medium saucepan, add butter. 
• Over medium-high heat, melt butter. 
• Add onion and bell pepper sauté until onion is transparent.
  
• Mix in roast beef; heat until beef is warm. 
• Divide beef mixture evenly into 4 portions. 
• Fill each roll with beef mixture. 
• Top each sandwich evenly with cheese.