Chicken with Cider and Lemon

4 chicken thighs

2 onions, cut into 8 wedges each

1 lemon, cut into 8 wedges

1/2 cup white wine 

1/2 cup chicken stock

1 1/2 cups apple cider 

1 tablespoon whole grain mustard

3 tablespoons butter

Salt and pepper

Vegetable oil 

Heat oven to 400F. 

Heat 2 tablespoons oil in a medium ovenproof skillet on medium heat. Season chicken with salt and pepper and add to pan, skin side down. 

Cook without turning until skin is golden brown, about 4 minutes. Turn, scatter onions and lemon around chicken and transfer pan to oven. Cook until chicken reaches 165F on an instant-read thermometer. 

Remove chicken from pan and cover with foil. Place pan back on medium heat and add wine and stock. Bring to a boil and cook until reduced by about half, 3 minutes. Add cider and reduce again by about half, 5 minutes more. Remove from heat and stir in mustard and butter. Adjust seasonings and add chicken back to pan to serve.