Cut potatoes into half-inch pieces and peppers into 1-inch chunks; toss with sausage links on a sheet pan with olive oil, rosemary, salt and pepper.
Roast at 450°F for 15 minutes, stir, then continue roasting for 5 minutes more until sausage reaches 160°F internal temperature.
Drizzle balsamic vinegar over the pan and toss gently.
Divide sausage and vegetables among four plates and serve hot.