Preheat the oven to 375°F. Cut potatoes into 1-inch pieces, ensuring even cooking.

Slice the onion into quarters and remove seeds from peppers, cutting into 1-inch pieces.

Toss potatoes, onions, peppers, olive oil, salt, pepper, rosemary, and garlic powder in a large bowl until evenly coated.

Spread the mixture evenly on a prepared baking sheet. Roast for 15 minutes.

Add sausage slices to the baking sheet. Continue roasting for an additional 25 minutes, tossing once or twice.

Ensure sausages are cooked through and vegetables are tender and crispy before serving.