Heat oil in a large skillet over medium-high heat. Add onions and cook 4-5 minutes or until tender. Add the gravy and roast beef. Cook until heated through; stirring occasionally.

Place bread on a shallow foil-lined pan. Divide roast beef mixture evenly on the bread slices. Top each slice with provolone cheese.

Broil in oven 1 minute or until cheese is just melted.