Ensure the shrimp is peeled and deveined. I personally remove the tails but if you prefer to keep them on that's up to you. Wash the shrimps thoroughly under cool water and drain.
Add the soy sauce to the shrimps and toss.
Make three cuts on the underside of each shrimp and slowly straighten each one out and lay them flat. The cuts should go no more than halfway through.
Roll each shrimp through the cornstarch and set aside.
Add enough oil to a pan or wok so that the shrimps will be fully submerged once added. Heat the oil to 375°F (190°C) and maintain that temperature.
While the oil is heating, combine the ice cold water and egg together. It's very important that the water is as cold as possible.
Add the flour all at once and mix together until a loose batter is formed.
Holding a shrimp by its tail end, dip it into the batter and drag it back and forth a couple times to ensure an even coating on all sides.
Hold the shrimp over the bowl to allow any excess batter to drip off.
Add the shrimp one at a time (up to three in a small pot) into the preheated 375°F (190°C) oil and fry until golden brown (approximately 2 minutes) Remove from the oil and place on a plate lined with paper towels so that any excess oil is soaked up.
Serve or use immediately.