Warm Potato Salad with Bacon-Mustard Dressing

Preheat oven to 450 degrees F. Coat a large roasting pan with cooking spray.

Toss potatoes, oil, rosemary, 1/2 teaspoon salt and 1/4 teaspoon pep per in the pan. Arrange cut-side down; roast for 10 minutes. Scatter onion on top (do not stir); cook until the potatoes are golden brown on the bottom, 10 to 15 minutes more. Stir in apples; cook until tender but still hold their shape, about 5 minutes more.

Meanwhile, cook bacon in a large skillet over medium heat, turning once, until crisp, about 10 minutes. Drain on a paper-towel-lined plate; crumble. Off the heat, whisk vinegar, mustard and the remaining 1/4 teaspoon each salt and pepper into the drippings in the pan, scraping up any browned bits.

Drizzle the apples and vegetables with the dressing, sprinkle with bacon and stir to coat. Serve hot or room temperature.