Flatten chicken to 5mm thickness between plastic wrap or greaseproof paper. Mix egg and water. Mix breadcrumbs, salt, pepper and garlic powder. Coat chicken with flour, dip into egg mixture and coat with breadcrumb mixture.
Heat butter or margarine and oil in 30cm frypan over medium heat. Cook chicken for 8 to 10 minutes, turning once, until juice is no longer pink when centers of thickest pieces are cut. Remove chicken from frypan using tongs; keep warm.
Stir lemon juice and wine into drippings in frypan. Heat to boiling; pour over chicken. Sprinkle with chopped fresh parsley and serve with lemon wedges for garnish.