Place chicken in a large zip-top plastic freezer bag. Add buttermilk and hot sauce; seal and refrigerate 2 hours. Remove chicken from buttermilk mixture; lay flat on baking sheet. Heat oil to 350° F. Combine salt, garlic powder and pepper. Sprinkle chicken with seasonings: set aside. In a large but shallow dish (such as a 13 x 9-inch pan) combine corn starch, flour, baking powder and water; mixing well to make a batter. Dip chicken into batter; a few pieces at a time being careful to allow excess to drip off. Using tongs, slowly place chicken into hot oil. Cook in small batches, turning frequently 15-20 minutes or until evenly browned and done. Chicken should reach 165-170° F. using a meat thermometer. Drain on wire rack over paper towels.