In a medium, nonreactive container, mix the soy sauce, brown sugar, sherry, coffee, and 2 tablespoons olive oil. Place chicken legs in the mixture. Cover, and marinate in the refrigerator 3 to 4 hours.
Remove chicken from the marinade mixture, and set aside. Transfer the marinade to a medium saucepan, and bring to a boil.
Heat remaining olive oil in a medium skillet over medium-high heat. Season chicken with pepper, and brown on all sides in the skillet. Pour the hot marinade mixture into the skillet. Reduce heat, and simmer 30 minutes, or until chicken is no longer pink and juices run clear. Cool slightly before serving.
