For the filling (or use 1 pound ground beef and the spices; see Step 2 below)
- 1 cup whole walnuts
- 4 ounces baby bella (cremini) mushrooms
- 1 tablespoons soy sauce or tamari (or coconut aminos for soy free)
- 1 tablespoons ketchup
- 1/2 teaspoon each fennel seeds, dried oregano, smoked paprika, onion powder, and garlic powder
- 1/4 teaspoon each kosher salt and black pepper
- 2 tablespoons olive oil, divided
For the stuffed peppers
- 6 multi-colored bell peppers (red, yellow and green)
- 3/4 cup dry short grain rice or 2 cups cooked (reheated to warm with a splash of water and a pinch of salt)
- 1/2 cup pizza sauce (purchased or homemade)
- 4 ounces fresh mozzarella balls (or cut into bite-sized chunks)
- 3/4 cup shredded mozzarella, plus more for sprinkling
- 1/4 teaspoon kosher salt
- 2 to 3 tablespoons grated Parmesan cheese, and/or Italian panko or bread crumbs (omit for gluten-free)