Trim the thighs of any excess fat. Season with salt and pepper. Heat the oil in a large, heavy skillet and brown the thighs well on both sides over medium heat, about 7 to 8 minutes. Remove the thighs to a plate and cover.

Cook the garlic and diced pepper in the same pan for 3 or 4 minutes. Add the chicken broth, marmalade and mustard and mix well. Bring to a boil and cook until the sauce has reduced by about 1/3 volume. Stir together the vinegar and cornstarch and whisk this into the broth mixture and cook until thickened. Season with salt and pepper.

Reduce the heat to a simmer and return the chicken to the pan. Cook over low heat until the thighs are cooked through, about 15 minutes. Place the thighs onto a platter and spoon the sauce on top. Sprinkle with chopped parsley and serve immediately.