From Fine Cooking
3 tbsp. extra-virgin olive oil
3 tbsp. whole-grain Dijon mustard
1-1/2 tbsp. balsamic vinegar
1/2 tsp. kosher salt, plus more as needed
1/2 tsp. freshly ground black pepper
8 chicken thighs (about 6 oz. each), trimmed of excess fat and skin
1 medium-large (12 oz.) sweet potato, peeled and cut into 1/2-inch pieces
4 medium parsnips (6 oz. total), peeled and cut into 1/2-inch pieces
4 small shallots, lobes separated, peeled and halved through the root end
3 strips bacon
1/4 cup coarsely chopped fresh flat-leaf parsley
Stir together the oil, mustard, vinegar, 1/4 tsp. of the salt, and 1/4 tsp. of the pepper in a large bowl. Add the chicken and toss to coat. Cover with plastic wrap and marinate in the refrigerator, turning occasionally, for at least 1 hour and up to 8 hours.
Heat the oven to 425°F.
Arrange the chicken skin side up on one end of a large rimmed baking sheet and drizzle with any remaining marinade. At the other end of the baking sheet, toss together the sweet potato, parsnips, shallots, and the remaining 1/4 tsp. each salt and pepper. Spread into a single layer. Sprinkle the chicken and vegetables lightly with a little more salt and roast for 20 min. Baste the chicken with the pan juices using a brush and stir the vegetables. Continue to roast, basting and stirring every 10 min., until the chicken is burnished—deeply browned—and the vegetables are tender, about 30 min. more.
Meanwhile, cook the bacon over medium heat in a large skillet until crisp, 5 to 8 min. Drain the bacon on paper towels. When the bacon is cool enough to handle, crumble it and toss with the parsley.
When the chicken is done, stir the vegetables and transfer them to a serving bowl with a slotted spoon. Toss with half of the bacon mixture. Baste the chicken and transfer with tongs to a serving platter. Sprinkle with the remaining bacon mixture, and serve hot.