Prick the potatoes all over with a fork and place on a plate. Cook in the microwave oven for 6 to 8 minutes or until tender, turning halfway through cooking. Set aside.
In non-stick skillet over medium-high heat, brown the mushrooms, onion and bell pepper in half of the butter. Season with salt and pepper. Keep warm.
In another non-stick skillet over high heat, brown the beef in the remaining butter. Season with salt and pepper. Add to the vegetables.
Place the potatoes in the hot skillet that was used for cooking the beef. With a potato masher, crush the potatoes down until ¾ inch (2 cm) thick. Deglaze the skillet with the broth and mustard. Sprinkle the potatoes with the cheese. Reduce the heat to low. Cover and cook for 3 minutes or until the cheese has melted.
Serve the potatoes over the vegetables and beef. Garnish with sour cream and a knob of butter, if desired.
This recipe doubles easily.
Recipes with the "Healthy Pick" stamp have been evaluated by a registered dietitian member of the Ordre professionnel des diététistes du Québec.