Peel the shrimp, leaving the tail and the segment at the base of the tail intact. (If using shrimp with heads, remove the heads.) Make a shallow slit along the back of the shrimp and remove the vein (the dark string).
Place the shrimp in a bowl, sprinkle them with salt, and gently rub it in. Then, add starch and water, and gently rub them in again. Rinse the shrimp under running water, and thoroughly pat them dry with paper towels.
Cut off the tip of the tail at an angle, then run a knife along the surface of the tail to release any trapped water.
Place the shrimp on a cutting board with the belly side up, and make shallow diagonal cuts, about one-third of the way through, across the segments (about four to five cuts in total).
Turn the shrimp so the back is facing up, and gently press it against the board with your fingers to break the muscle fibers. After pressing, shape it into a straight, even line.
Lightly sprinkle the shrimp with salt and pepper.
Crack the egg into a bowl and beat it. Prepare two containers, one with flour and the other with panko breadcrumbs.
Coat the shrimp in this order: flour, beaten egg, and panko breadcrumbs. Once the flour is applied, gently shake off any excess with your hands. Make sure the shrimp are thoroughly coated with panko so that the flesh is completely covered.
Heat oil in a pot until it reaches 340-355℉ (170-180℃). Once the oil is hot, carefully add the shrimp one at a time. Deep-fry them for about 2-3 minutes until they turn golden brown.Be careful not to add too many pieces at once, as this can cause the oil temperature to drop significantly. The shrimp should occupy no more than about two-thirds of the oil’s surface area.If you don't have a thermometer, drop a few panko breadcrumbs into the oil to test the temperature. When the breadcrumbs float to the surface at a moderate speed without touching the bottom, it indicates that the oil is ready. Remove the shrimp from the oil and let any excess oil drain off on a wire rack. If there are any fried bits left in the oil, skim them out with a mesh skimmer or strainer, then repeat the frying process (step 9) until all the shrimp are fried.
Serve your ebi fry on a plate with fresh vegetables if desired, and feel free to enjoy it with Japanese tartar sauce, Worcestershire sauce, salt, lemon wedges, or your favorite condiments.