In a large bowl, mix egg yolk, sake, vinegar and water and keep cold in the refrigerator.
In another bowl, combine flour, corn starch and baking soda and keep cold in the refrigerator.
Preheat oven to 200ºF or keep warm setting. Set a baking rack on a baking pan.
With a small knife, make 3 shallow slits horizontally across the inside curve of each shrimp and gently press shrimp flat on cutting board. This will prevent the shrimp from curling during cooking. Cut off the pointy tip of the tail of shrimp to prevent oil from splashing.
Fill a large saucepan about 1/3 to 1/2 full with vegetable oil, and heat to 350°F over moderate heat.
Remove bowls from refrigerator and whisk in the flour mixture to the egg water. Do not over-mix; allow some lumps to remain. The batter should be thinner than pancake batter. Adjust with water if necessary to reach desired thickness.
Hold the shrimp by the tail, lightly dust with flour (not included in ingredients), dip in batter and drop in oil one by one. Don't crowd the oil with foods while frying, or the temperature will drop and the food will absorb more oil. Turn with a tong once or twice and cook until golden, about 2 minutes. Transfer to the baking rack to drain and place in the oven to keep warm.
Keep oil at 350°F and, using a skimmer, remove any residual bits of batter from the oil before adding the next batch. Fry the vegetables in the same manner, except for shiso leaves.
To fry shiso leaves, lay each leaf on top of the batter to coat only one side, then drop into the oil, battered-side-down, and fry without turning until underside is golden, about 1 minute. Transfer to the baking rack and keep warm in the oven.
Make the dipping sauce. In a small saucepan, stir together dashi, soy sauce and mirin over medium heat. Bring to a simmer, then remove from heat.
Serve tempura with dipping sauce. Add grated ginger and daikon radish to the dipping sauce if preferred.