Philly Cheese Steak Sandwich

4-5 slices of sliced roast beef
1 slice of provolone cheese
1 small onion sliced thin
1 green bell pepper sliced thin
1 sub bun
butter

In a meduim sauce pan over meduim heat, saute bell pepper and onion. In a lightly buttered skillet over meduim-high heat, cook roast beef until lighly browned. Grill sub buns till lightly brown. Layer roast beef, provolone, onion/pepper mixture on sub bun.