In a small bowl, mix together mayonnaise, Dijon mustard, and minced garlic. Set aside.
Heat 1 tablespoon of olive oil in a skillet over medium heat. Add the sliced onion and green bell pepper, season with salt and pepper, and cook until they are soft and slightly caramelized, about 7-10 minutes. Remove from the skillet and set aside.
In the same skillet, add the remaining tablespoon of olive oil. Add the thinly sliced prime rib and cook for a few minutes just until heated through. Be careful not to overcook, as the meat is already cooked.
Preheat the oven's broiler and cut the sandwich rolls or ciabatta bread in half.
Spread the mayonnaise and mustard mixture on both sides of each roll.
Divide the warm prime rib among the four rolls. Top with the cooked onions and bell peppers.
Place a slice of provolone cheese on top of each sandwich.
Place the open sandwiches under the broiler for 1-2 minutes, or until the cheese is melted and bubbly. Watch closely to avoid burning. Assemble the sandwiches and serve immediately.
Notes
- You could also use baguettes, artisanal loaves, or even hamburger buns for a different variety of textures and flavors.- Watch the sandwiches closely while broiling to ensure the cheese melts without burning the bread. The broiling time might vary depending on the oven, so it's important to stay close by.