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.
Discard the foot of the shiitake mushrooms.
Slice the baby aubergines lengthwise, ensuring that the tail remains. Fan out the slices, and keep in place with a skewer.
Slice the asparagus in half lengthwise.
Peel the prawns, but keep the tail. Spear each prawn with a skewer in order to keep them straight during the cooking process.
In a fryer, or a large sauce pan, heat the fryer and sesame oil until they reach 180'C.
Dip each ingredient in the batter, shaking off any excess before dropping in the hot oil. The tempura is cooked when the batter just begins to colour.
Remove skewers and serve immediately.
Bring the water to the boil. Add the dashi powder. Remove from the heat. Stir in the soya sauce.
Peel the daikon radish, and grate on a fine grater. Do the same with the ginger.
The grated ginger and daikon are serve separatly, 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.»