Devein and peel the shrimp, but keep the tail on. Make 3 or 4 slits on its underside.
Bend back the shrimp backwards (bending the outer curve) until you feel a slight pop along each section. Make small incisions to cut the sinew, and pull the shrimp straight.
Slice the eggplant in half lengthwise. Leaving about 2 cm of the stem ends, and make about 5mm wide cuts along the length of the eggplant Soak in water and drain.
Scoop out the seeds and fluffy insides of the kabocha squash, and chop into 5mm wide pieces. Remove the stalks of the shiitake mushrooms and cut in half.
Peel the lotus roots and slice into 5mm wide pieces. Soak in water with a little vinegar and drain.
Put some mayonnaise into a bowl. Add water in batches and mix well. When mixed evenly, add the flour. Stir until it's still slightly floury.
Dredge ingredients prepped in steps 3, 4, 5, 6, and shiso leaves in the batter prepped in step 7. Deep-fry in vegetable oil.
Story Behind this Recipe
Here's an easy recipe to make crispy tempura with mayonnaise. The emulsified oil in the mayonnaise disperses onto the coating and its moisture becomes easier to evaporate. That's why you get a more crispy result even if you follow your standard deep-fry routine for the tempura.
Soaking the lotus root in water with a little vinegar gets rid of its bitterness and also makes them whiter. If you use cold water in the batter, it becomes even more crispy when deep-fried.