Cut the peppers and onions into strips and set aside.
Place a large skillet over a medium-high flame and heat the olive oil.
Add the sausage and brown on all sides, about 8–10 minutes. Prick the sausage with a fork as it cooks to release more flavor into the pan.
Remove the sausage to a plate and set aside.
In the same skillet, add the onions and sauté until softened and lightly caramelized, about 7–10 minutes.
Add the peppers and cook until they begin to soften and cook down, about 15 minutes.
Return the sausage to the pan and pour in the white wine. Cook for 1 minute, scraping up any browned bits from the bottom of the pan.
Season with salt and pepper to taste.
Add the olives, capers, and water. Lower the flame to medium, cover, and cook for 15–20 minutes, or until the sausage is fully cooked and the peppers are tender.
Garnish with fresh parsley and serve hot with crusty Italian bread.