Preheat oven to 350°.
Half and wash peppers and place them in the oven for 15 minutes. (cut side up)
In a medium saucepan add mushrooms, sliced onions, garlic, and spices. Saute for 5-10 minutes.
Add walnuts, sun-dried tomatoes, and balsamic vinaigrette, and cook for an additional 5 minutes.
Pull peppers out of the oven and stuff them with the mushroom mixture.
Place them back into the oven for an additional 10 minutes.
Serve with topped with fresh herbs such as parsley.