Vegetable oil
1 large package of chicken thighs, (10 or 12) or use a mix of legs and thighs
10 onions, peeled and thinly sliced
1 tbsp dried thyme
1 cup sherry
1/4 cup Dijon mustard
Sprinkled sea salt and freshly ground black pepper, to taste

Heat a large skillet over medium-high heat and add a splash of oil, enough to lightly coat the bottom. Add the chicken pieces, skin side down and brown them well on each side. Remove chicken from pan and place on a paper towels to absorb the oil.
Put half the onions into a slow cooker and stir in the thyme, sherry, mustard and salt and pepper. Add the chicken pieces and cover with the rest of the onions. Season again with salt and pepper. Add the lid, set to medium or low and cook for at least six hours or longer. The onions will turn golden brown, shrink dramatically and release lots of moisture for the chicken to braise tender in.