Using a meat grinder, grind the Top Sirloin (1.5 pound).
On a skillet over medium-high cook the ground sirloin. Keep cooking until nice and brown. Remove and set aside.
Add Oil (1 tablespoon) to the same skillet used to cook the ground sirloin. Add Onion (1), Cubanelle Pepper (1) and Mushroom (12 ounce). Season with Salt (1/2 teaspoon). Cook over medium-high heat until you've reached the desired doneness on the veggies.
Add the ground sirloin back in and season with Worcestershire Sauce (2 tablespoon), Garlic Powder (1 1/2 teaspoon), Ground Black Pepper (1/2 teaspoon), Crushed Red Pepper Flakes (1/4 teaspoon). Stir thoroughly to mix seasonings. Taste and adjust Salt and Pepper (to taste) if needed.
Sprinkle the Mozzarella Cheese (16 ounce) over the ground sirloin and turn off the heat. Mix well.
Serve on bread or buns of choice and top with Fresh Baby Spinach (to taste).