Clean the shrimp under running water and remove the heads. To devein the shrimp, pull the vein from the opening of the shrimp where you removed the head.
To straighten your shrimp, score very shallow (⅛ inch) cuts on the belly of the shrimp. (You can also use skewers to straighten the shrimp if you don’t want to score them). Straighten the shrimp on a plate over paper towels to dry the shrimp off.
In a heavy bottomed pot, add about 2 inches of oil from the bottom of the pot. Heat the oil to 350 °F degrees.
In a mixing bowl, add the flour and ½ cup of potato starch and mix thoroughly.
In another bowl, add the egg and mix in the cold vodka. Then add the carbonated water.
Carefully, add the wet batter into the mixing bowl and use the chopsticks to mix the batter in swift movements. Try to lift the bowl and move the bowl in round movements while stirring with the chopsticks. Make sure to not overmix the batter or your tempura will end up chewy. You should have some lumps in your batter. The mixing process should take no longer than one minute.
In a separate bowl, add ¼ cup of potato starch in a shallow bowl. Cover the shrimp in a light layer of potato starch.
Holding the shrimp tail, dunk the shrimp into the batter and cover thoroughly. Carefully lower the battered shrimp into the oil. To add extra crispy tendrils of tempura, dip your hand back into the batter and drip small drops of batter onto the frying shrimp.
Turn the shrimp after about one to two minutes. Remove the cooked shrimp from the oil and place over paper towels on a cooling rack, then serve with tetsuya sauce.
In a small sauce pot, add the water over a medium-low heat.
Add the dashi mix, soy sauce, and mirin.
Heat until it boils for one minute and then remove from heat.