Prepare the prawn and vegetables and set aside. *2
Place the flour and add icey cold water and mayonnaise. Combine them together briefly (don't over-mix or it will be too gooey).
Set aside in fridge until all ingredients and oil is ready.
Fill a deep pan or deep-fryer with vegetable oil and heat until 180c.
Add each ingredient (prawn & vegetable) to the batter individually to coat them and put them into the oil.
When the prawn and vegetable is cooked, if you lift them up out of cooking oil with a pair of chopsticks you can feel tiny vibration.
When the ingredients are cooked, place them onto a plate lined with a paper towel to absorb the excess oil.
Continue to coat and fry each ingredient until all done.
Add the mirin to a small sauce pan and boil on high heat for about 1 minute (this will allow all the alcohol to evaporate).
Add the water, soy sauce, and dashi powder and bring to a boil.
Place the sauce in a bowl and allow it to cool down then serve with the Tempura.
Pour about ¼ cup of Tentsuyu in a small bowl with about 1 tbsp of grated daikon to serve with Tempura. *3
