Combine flour, cornstarch, salt & pepper. Beat together egg, 1/4 cup oil & ice water; add egg mixture all at once to dry ingredients, beating with mixer. (Do not overmix. Batter will be lumpy.) Set bowl of batter inside larger bowl filled with ice water. Dip fish into batter; deep fry in oil heated to 375 for 3 minutes, or until golden brown. Drain well on paper towels; serve immediately. Serve with soy sauce & lemon slices.