Beat the egg in a bowl and add the iced water. Lightly mix in the flour,
rubs and salt with a fork and beat gently.
TIPS:
1. The water must be as cold as possible, as this prevents the batter from absorbing too much oil, keeping it light and crispy.
2. Do not over beat and do not worry if you have a few lumps.
3. Prepare this batter just before use.
4. Tempura should be cooked in oil of about 180C/350F - if the vegetables sink to the bottom, the temperature is too high.
5. Cooking time will vary, for example, butternut or potato will take longer to cook than green beans or zucchini
