Sheet-Pan Bratwurst Sandwiches with Red Potato and Kale Salad

Steps

1. 1Adjust oven rack to middle position, place rimmed baking sheet on rack, and heat oven to 425 degrees. Toss potatoes with 2 tablespoons oil, ½ teaspoon salt, and ¼ teaspoon pepper in bowl. In separate bowl, toss onions with 1 tablespoon oil.
2. 2Place bratwurst on 1 side of hot sheet and spread potatoes, cut side down, on other side. Scatter onions around bratwurst on sheet. Roast until sausages register 160 degrees and potatoes are tender, 25 to 30 minutes, flipping bratwurst halfway through roasting.
3. 3While the bratwurst and vegetables are roasting, whisk remaining ¼ cup oil, vinegar, 2 tablespoons mustard, ½ teaspoon salt, and ¼ teaspoon pepper together in large bowl.
4. 4Remove sheet from oven. Add potatoes to dressing in large bowl and toss to coat; cover to keep warm. Tent onions and bratwurst, still on sheet, with aluminum foil to keep warm. Place hot dog buns directly on rack and toast until lightly browned, about 5 minutes.
5. 5Remove rolls from oven. Spread remaining 2 tablespoons mustard evenly into rolls, then top with bratwurst and onions. Add kale and radishes to potatoes and toss gently to combine. Serve immediately with sandwiches.