2Slice the sausage links in half lengthwise. Cut your peppers into thick strips, removing the seeds. Slice the onions into thick wedges. Mince the garlic.
3Toss the sausage, peppers, onions, and garlic on a large sheet pan with olive oil, red pepper flakes, oregano, salt, and pepper. Spread everything in a single layer.
4Roast for 20-25 minutes, stirring halfway through, until the sausage is cooked through and the peppers are tender with some charred edges.
5Drizzle with balsamic vinegar and taste for seasoning. Add more salt or pepper if needed.