Preheat the oven to 425˚. Spread the peppers and onions on a baking sheet. Drizzle with the olive oil, sprinkle with the sage, salt and some pepper and toss, breaking up the onions a bit as you do.
Put the sausages in and around the vegetables on the baking sheet.
Bake until the sausages are cooked through and the vegetables are tender, 30 to 35 minutes.
Slice the sausages and serve on rolls with the roasted vegetables.
