The grinder is a specialty served at the Iowa State Fair, home to some of the nation’s richest and most waist-expanding treats. Still a hefty meal-in-one, this rendition takes a lighter approach. We cut the size in half (always a good place to start) and substituted fresh mushrooms for some of the fatty meat.
Place mushrooms in a food processor, and pulse until finely ground. Reserve.
Heat canola oil in a medium nonstick skillet over medium-high heat. Add sirloin and sausage. Cook until golden brown, breaking up meat with a spoon, about 5 minutes; remove with a slotted spoon and reserve. Add onion to pan and reduce heat to medium-low; cook until soft, about 4 minutes.
Add mushrooms and red pepper, if desired, to the pan, and mix well. Cook until mushrooms are darker in color, about 5 minutes. Add garlic, and cook 30 seconds until fragrant. Add pasta sauce; stir to blend. Return cooked sirloin mixture to pan; bring sauce to a simmer and cook 2 minutes.
Divide mixture among buns and top with mozzarella cheese. Broil in oven or toaster oven until cheese melts. Serve warm.