Make the tentsuyu sauce by mixing together all the ingredients. Set aside.
Prepare the shrimps
Place cleaned the shrimps on a plate in a single layer and sprinkle two tablespoons of flour over them. Toss lightly to cover the shrimps completely with a thin coating of flour.
At this stage, start heating the cooking oil in a wok or frying pan. Make sure that the oil is at least three inches deep.
Make the batter
Mix together the flour, starch and egg with half a cup of cold water.
Add ice to the batter and mix until you have a rather thin but not watery batter. The consistency should be thinner than pancake batter.
Fry the shrimps
Test the temperature of the oil. The ideal temperature is 350F. If you don't have a thermometer, drizzle in a little batter. If it sinks, the oil is not hot enough. If it browns within a few seconds, the oil is too hot. Adjust and keep testing until you get the correct temperature.
Dip each shrimp in the batter then drop into the hot oil. Fry no more than two or three pieces at a time.
Dip your (clean) fingers in the batter then drizzle the batter directly over and around the shrimps.
Fry the shrimps for one to two minutes or just until crisp, flipping halfway through for even cooking.
Scoop out and move to a rack or strainer.
Scoop out any excess batter in the oil and move to a plate before frying the next batch.
Serve your ebi (shrimp) tempura immediately with tentsuyu for dipping.