Preheat oven to 450°F (230°C) with rack in middle.

Prepare parsnip fries. Scrub and quarter the parsnips lengthwise. If they are large, cut lengthwise into eighths. Toss with 1 tablespoon + 2 teaspoons olive oil (25mL) in a large shallow baking pan and sprinkle with 1/4 teaspoon salt (1.25 mL) and pepper. A cast iron frying pan also works well. Roast in oven at high heat, for 10 minutes, while preparing chicken. Toss.

Meanwhile, pat chicken dry, and then sprinkle with remaining salt. Heat remaining olive oil (1 Tbsp / 15mL) in a 12-inch (30.5 cm) heavy skillet over high heat until it shimmers, then brown skin side of chicken.

Transfer chicken, skin side up, to pan with parsnips, reserving skillet, and roast until chicken is cooked through and parsnips are tender and caramelized, about 40 minutes or until chicken reaches an internal temperature of 165°F (74°C).

While chicken roasts, reheat skillet with remaining olive oil, then add vinegar and chili pepper flakes and bring to a boil, stirring for 30 seconds. Pour into a cup and keep warm and covered.

Serve chicken and fries drizzled with spicy vinegar.