1.For the dipping sauce, combine sauces, the room temperature water, juice and onion in small bowl and whisk to combine.
2.Whisk egg and the iced water in medium bowl; stir in sifted flours all at once. Do not overmix; batter should be lumpy.
3.Heat oil in large saucepan. Dip fillets, one at a time, in batter; deep-fry, in batches, until browned lightly and just cooked through. Drain on absorbent paper. Serve with dipping sauce.
If serving whiting tempura as finger food, cut fish fillets into bite-sized pieces before coating in batter. Place fried fish in slow oven to keep warm while cooking remaining batches.Note