Preheat the oven to 400°. Position a rack in the upper third. On a large rimmed baking sheet, toss the potatoes with 1 tablespoon of the olive oil and season with salt and pepper. Spread the potatoes in a single layer and roast for 12 minutes, turning once, until barely cooked. Add the sausages and roast for about 10 minutes longer, turning them once, until the potatoes are tender and the sausages are lightly browned and heated through. Blot the potatoes and sausages dry with paper towels and cut the sausages into 1/3-inch-thick slices. Transfer to a large bowl.