1. Combine the balsamic vinegar, 2 tablespoons olive oil, apple cider vinegar, maple syrup, salt and pepper in a medium mixing bowl and stir to combine.

2. Add chicken thighs to the marinade and stir to ensure all thighs are coated. Cover the bowl and refrigerate to marinate for a minimum of 30 minutes, up to overnight (the flavor is best if left overnight).

3. Preheat the oven to 425ᵒ F.

4. Add the remaining 2 tablespoons of olive oil to a large oven-safe skillet over medium-high heat. Swirl to coat the pan with oil. When hot, add the chicken thighs and cook for 2-3 minutes on each side. Add the onion slices in an even layer around the chicken and pour the leftover marinade over the top. Sprinkle the cranberries on top of the onion slices and place in the oven to roast for approximately 20 minutes, or until the chicken is cooked (the thickest part of the thigh should read 165ᵒ F on a meat thermometer).

5. Serve while hot.