Heat oven to 400 F.
In large skillet, heat oil over medium-high. Add onion and garlic and cook about 3-5 minutes. Add sausage and break up with spoon. Cook until browned about 10 minutes. Add tomatoes, 1 cup water and bulgur; cook until thickened about 10 minutes.
Fill peppers with bulgur mixture. Arrange peppers in a baking dish just large enough to hold them. Top each pepper with 1/4 cup pasta sauce and sprinkle with mozzarella cheese. Add 1/4 cup water to baking dish. Cover with lid or aluminum foil. Bake pepper until tender, 35-40 minutes. Remove foil and set on broil for 2-3 minutes to brown the cheese, if desired. Garnish with Italian parsley and serve.