In a large skillet, cook sausage over medium heat until no longer pink. Add the potatoes, onion, green pepper, salt and pepper. Cook over medium-high heat for 18-20 minutes or until the potatoes are browned.
Stir in mushrooms. Pour eggs over the potato mixture. Arrange tomato slices on top. Sprinkle with cheese.
Cover and cook over medium-low heat for 10-15 minutes or until eggs are completely set (do not stir). Serve with sour cream and salsa if desired.