Fried Enoki Mushrooms

In a small bowl, combine Japanese mayonnaise, sriracha, lemon juice, and toasted sesame oil. Mix well and set aside until serving.
Trim off the roots of the enoki mushrooms, but leave some of the connected parts so they don't separate into individual strands. Rinse under cold water and dry them with a salad spinner or paper towels. Slice the mushrooms lengthwise through the base to make 3 or 4 thin slabs.
In a medium bowl, whisk together the flour, cornstarch, salt, and baking powder. Add cold water and mix until just combined. The batter should have the consistency of thin paint. It should easily flow and run off the mushrooms but still be thick enough to coat the mushrooms. Add extra flour or water as necessary.
Heat about 1 inch of oil to 375°F and try to maintain a temperature around 350°F during frying. The temperature will decrease by about 25°F when you first add the mushrooms.
Working one at a time, dip mushroom slices in the batter, shake off excess, and place in the hot oil. Fry 3-4 pieces at a time for 2-3 minutes per side until golden. Drain on paper towels and serve immediately with spicy mayo on the side.