Prepare the shrimp:Pat the shrimp completely dry with paper towels to ensure a crispier fry and avoid splattering.
Make the tempura batter:In a medium bowl, whisk together flour, cornstarch, baking powder, and a pinch of salt. Slowly add the ice-cold water while stirring gently—don’t overmix; lumps are totally fine!
Heat the oil:In a deep, heavy-bottomed pot, heat about 2 inches of oil to 350°F (175°C). Use a thermometer for accuracy if available.
Fry the shrimp:Dip each shrimp into the batter, allow the excess to drip off, then carefully place into the hot oil. Fry in batches for 2–3 minutes, turning once, until golden and crispy.
Drain the shrimp:Remove with a slotted spoon and transfer to a paper towel–lined plate. Keep warm while frying the remaining shrimp.
Serve and enjoy:Serve immediately with soy sauce or traditional tempura dipping sauce. Add lemon wedges for a zesty touch.