Cut potatoes, bell pepper, onion, and sausage into half inch pieces. Quarter mushrooms (if large, cut into 6 pieces).
Cook sausage pieces over medium heat in a large skillet. Remove and set aside. Melt oil in same skillet over medium-high heat. Add onion, bell pepper, and potatoes. Cook for 7-8 minutes until vegetables are starting to brown.
Add white wine to deglaze pan and scrape off pieces that are stuck to bottom and sides. Add mushrooms and garlic and continue cooking until potatoes are tender (7-8 minutes). Add Sausage back in and stir. Top with grated cheese, and if desired, green onion and parsley.