Lemon dipping sauce
1.Shell and devein prawns, leaving tails intact. Make three small cuts on the underside of each prawn, halfway through flesh, to prevent curling when cooked.
2.Halve onion from root end. Push four toothpicks at regular intervals through each onion half to hold rings together; cut in between toothpicks.
3.For tempura batter, whisk egg white in large bowl until soft peaks form; add soda water, whisk to combine. Add sifted flours; whisk to combine (batter should be thin and lump free).
4.For lemon dipping sauce, heat vinegar, sugar and soy in small saucepan, stirring, until sugar dissolves. Remove from heat, add rind; stand 10 minutes. Strain sauce into serving dish; discard rind. Sprinkle sauce with onion.
5.Heat oil in wok. Dust prawns, onion, fish, capsicum, kumara and zucchini with flour; shake off excess. Dip, piece by piece, into batter; deep-fry until crisp. Drain on absorbent paper.
6.Serve tempura with dipping sauce and lemon wedges.
For best results, both food and batter should be very cold at the time of cooking. Only fry small batches of food at a time, making sure that the oil returns to the correct temperature before adding the next batch.Note