Hot Mustard Chicken Thighs

Ingredients:
(consider all the spices “to taste” and adjust to your liking)
8-10 chicken thighs
1/2 cup Dijon mustard
1/4 cup packed brown sugar
1/4 cup red wine vinegar
1 tsp mustard powder
1 tsp freshly ground black pepper
1 tsp salt
1/2 tsp ground dry chipotle
cayenne to taste
1 onion sliced into rings
4 cloves minced garlic
vegetable oil for the pan and top of chicken