Using a fork or a pair of chopsticks, mix together the corn starch and flour. Add the water in one go, and stir. The final batter should be lumpy and have the same thickness as milk.
For best results, make sure that the water is ice cold.
Slice the red pepper into thin sticks.
Top and tail the carrots, peel, and cut into a thin julienne.
Shred the bok choi into large ribbons.
In a fryer, or a large sauce pan, heat the fryer to 175'C.
The vegetables can all be mixed into the batter and fried as tempura fritters, or you can dip each vegetable separately. Shake off any excess batter before dropping in the hot oil. The tempura is cooked when the batter just begins to colour.
Briefly drain the cooked fritters on paper towels and serve immediately.
Bring the water to the boil. Add the dashi powder. Remove from the heat. Stir in the soya sauce.
Peel the ginger, and grate on a fine grater.
The grated ginger and dipping sauce are serve separately, and the diners help themselves to as little or as much as they want to mix into the tentsuyu (dipping sauce).
«Tentsuyu can be made several days in advance, and kept in the refrigerator until needed. It is usually serve hot or warm-ish in summer, but never cold, as it will render the tempura too soggy.»