Pat prawns dry with paper towels. Make three small shallow slits on the underside of each prawn to prevent curling. Lightly dust each prawn with 1 tablespoon flour—this helps the batter adhere.

Make batter

In a bowl, lightly beat the egg. Add ice-cold sparkling water and stir once or twice to combine. In a separate bowl, whisk together 60 g all-purpose flour, 40 g cornstarch, 20 g rice flour (if using), 1 tsp baking powder, 1 tsp salt, 1/4 tsp white pepper and 1/2 tsp chili flakes. Add the dry mix to the egg mixture and gently fold with a few strokes—do not overmix; a few lumps are fine. Keep the batter chilled in a bowl set over ice if possible to stay very cold.

Heat oil

Pour neutral oil into a deep-sided saucepan or fryer to a 6–8 cm depth (about 800 ml). Heat to 175°C (350°F). If you don't have a thermometer, test by dropping a little batter into the oil — it should sizzle and rise to the surface immediately and turn pale golden in about 30–40 seconds.

Fry prawns

Working in small batches (3–4 prawns), dip each floured prawn into the chilled batter, letting excess drip off briefly, then gently lower into hot oil. Fry until crisp and golden, about 2–3 minutes depending on size. Turn once if needed. Do not overcrowd the pan. Remove with a slotted spoon and drain on paper towels-lined tray. Maintain oil temperature between batches; adjust heat to keep it around 170–180°C.

Keep warm and serve

If making ahead, keep cooked prawns on a wire rack in a warm (100°C/210°F) oven for up to 15 minutes to stay crisp. Fry remaining prawns and finish plating immediately for best texture.

Spicy lemon mayo dipping sauce

Combine 100 g mayonnaise, 2 tablespoons fresh lemon juice and 1 teaspoon lemon zest in a small bowl. Add 1 tablespoon sriracha, 1/2 teaspoon gochujang (if using), 1/2 teaspoon honey and 1/2 teaspoon minced garlic. Whisk until smooth. Season with 1/4 teaspoon salt and 1/8 teaspoon black pepper. Taste and adjust heat or acidity — add more sriracha for spicier, more lemon juice for brightness. Chill for at least 10 minutes to let flavors meld.

Finish & garnish

Arrange tempura prawns on a serving plate. Spoon a generous portion of spicy lemon mayo into a small dipping bowl or drizzle lightly over prawns. Garnish with microgreens or chopped chives, a sprinkle of extra chili flakes if desired, and lemon wedges on the side. Serve immediately so the tempura remains crisp.