Remove skin from chicken. Rinse Chicken; pat dry. Spray a cold large skillet with nonstick coating. Preheat the skillet over medium heat. Brown chicken pieces on all sides in hot skillet.
Add 3/4 cup water, sherry, soy sauce, and garlic powder. Bring to boiling; reduce heat. Simmer, covered for 35 to 40 minutes or till chicken is tender and no longer pink. Transfer chicken to a serving platter; keep warm.
For sauce, stir together the 2 tablespoon water and the cornstarch; set aside. Cook and stir for 3 to 4 minutes or until celery is crisp and tender. Stir in the cornstarch mixture. Cook and stir till thickened and bubbly. Cook and stir for 2 minutes more. Serve chicken and sauce with hot cooked rice. Makes 4 servings.