Follow these simple steps to create the amazing Apple Cider Braised Chicken Thighs:

1. Season Chicken: Generously season the chicken thighs with salt and pepper on both sides.
2. Heat Oil: In a large, heavy-bottomed skillet or Dutch oven, heat the olive oil over medium-high heat.
3. Brown Chicken: Add the chicken thighs, skin side down, and sear until golden brown, about 5-7 minutes. Flip and brown the other side for an additional 5 minutes. Remove chicken from the skillet and set aside.
4. Sauté Onions: In the same skillet, add the sliced onions and sauté until they are softened and caramelized, about 8-10 minutes.
5. Deglaze Skillet: Pour in the apple cider, scraping up any browned bits from the bottom of the pan. Bring to a simmer.
6. Add Flavorings: Stir in the Dijon mustard, thyme, and cinnamon stick, mixing well.
7. Return Chicken: Nestle the browned chicken thighs back into the skillet, skin side up. Add the apple slices on top.
8. Braise: Cover the skillet and reduce the heat to low. Let it simmer for 40-45 minutes until the chicken is tender and cooked through.
9. Finish Sauce: Remove the chicken from the skillet and let it rest. Increase the heat to medium-high and stir in the apple cider vinegar. Let the sauce reduce for about 5 minutes.
10. Serve: Return the chicken to the skillet to coat it in the sauce and warm through before serving.