For the sandwiches:
2 cups leftover pot roast
8 slices sturdy bread
3 tablespoons butter, plus more for the bread
2 medium onions, thinly sliced
8 ounces sliced button mushrooms
2 cloves garlic, minced
Salt and pepper to taste
8 slices Colby cheese (or Swiss, or provolone, etc.)
For the sauce:
1/2 cup mayonnaise
3 tablespoons steak sauce (like A1)
Dash Worcestershire sauce
- Re-heat the pot roast in the microwave. Butter one side of all 8 slices of bread.
- Melt 3 tablespoons butter in a large skillet. Add onions and mushrooms and cook over medium-high heat, stirring frequently, until onion is softened and mushrooms are browned. Add garlic; season with salt and pepper and cook and stir for 30 seconds. Remove from heat.
- Heat a griddle over medium-high heat. Place a slice of cheese on the unbuttered side of 4 slices of bread. Top each slice with 1/2 cup of the pot roast, a generous portion of the onion and mushroom mixture, and the other slice of cheese. Repeat with all four sandwiches and top with the other slice of bread, buttered side out. Grill, flipping once, until both sides are browned and crispy.
- Combine all sauce ingredients. Serve the sauce with the patty melts.