3 russet potatoes
2 cups 1/2-inch cubes roast beef
1 onion, finely chopped
1 green bell pepper, thinly sliced
½ cup sliced fresh mushrooms
1 tablespoon vegetable oil
Place potatoes on a microwave-safe plate and prick skins with a fork. Cook in the microwave until slightly tender, 7 to 8 minutes. Cut into 1-inch cubes.
Combine potatoes, roast beef, onion, green bell pepper, and mushrooms in a bowl.
Preheat an electric skillet to 350 degrees F (175 degrees C). Coat with oil.
Spread potato mixture evenly in the skillet. Let cook, without stirring, until browned, about 5 minutes. Flip and continue cooking until second side is crisp, about 5 minutes more.