Steps

1. Shell the prawns, leaving the tail on. Cut off the tips of the tails, then score the undersides several times.
2. Use the aubergine whole if they are very small, otherwise cut them in slices.
3. Cut the beans in half.
4. To make the batter, beat the egg in a bowl, add the cold water and flour, and mix lightly.
5. Heat the oil in a heavy-based deep pan.
6. Dip the prawn, aubergine, and beans into the batter and deep-fry them until they float on the surface of the oil. Place them on kitchen paper to remove excess oil.
7. Place all the sauce ingredients in a small pan and bring them to a boil. Arrange the tempura on a bowl of rice and pour over the sauce.