Preheat and prep: Preheat your oven to 425°F (220°C). Line a large rimmed sheet pan with parchment for easy cleanup, or lightly oil it.
Slice the vegetables: Cut peppers into 1/2-inch strips and the onion into wedges.
Keep slices similar in size so they cook evenly.
Season: In a large bowl, toss peppers and onions with olive oil, salt, pepper, oregano, garlic powder, and smoked paprika. Add the vinegar and toss again to coat.
Arrange on the pan: Spread the vegetables in a single layer. Make space for the sausage links so everything makes contact with the pan.
Add the sausage: Place the sausage on the pan.
If they’re very thick, prick each link once or twice with a fork to prevent bursting.
Roast: Bake for 20 minutes. Flip the sausages and toss the vegetables. Roast another 10–15 minutes, until the sausage is cooked through (internal temp 160°F for pork, 165°F for poultry) and the peppers are caramelized at the edges.
Finish and serve: Sprinkle with chopped parsley and a squeeze of lemon.
Serve as-is, in warm rolls, or over rice or polenta. Add extra vinegar or hot sauce if you like a little punch.