First, cook your meat and saute your mushrooms (I add onions and fresh garlic when I I saute these ingredients.
Cook your Quinoa according to the instructions on the package and set aside.
Slice the tops off of the Peppers and place them face up in a deep baking dish. Add a small amount of water to the bottom of the dish. Make sure it's just enough to cover the bottom of the pan. This will create a steam for the veggies.
In a separate bowl, combine the cooked Quinoa, Mushrooms and meat.
Stuff each Pepper and top with cheese if you prefer.
Bake for about 20 minutes or until the pepper is soft.