2 tablespoons butter
1 cup sliced onion
1 cup sliced bell peppers (green and red)
1 cup sliced mushrooms
pinch of salt and pepper
4 slices provolone cheese
4 buns

Heat butter in a large skillet over medium heat.
Add onions, peppers, and mushrooms and saute about 10 minutes, until soft.
Season with salt and pepper and divide into four servings within skillet. Top each serving with provolone cheese and cover skillet to allow cheese to melt.
Scoop each serving on to a bun to enjoy.