Run a sharp knife down the back of each prawn, remove and discard the vein, press out flat like a butterfly and pat dry any excess moisture with some kitchen paper. Blend the roughly chopped ginger and spring onion with the sushi seasoning in a mini food processor to a coarse paste. Rub the paste into the prawns, dust them in the cornflour and set to one side.

Make the batter by beating the egg and carbonated water together in a bowl then lightly whisk in the flour and salt. Do not overwork the batter, a few lumps are fine.

Place the breadcrumbs into a shallow bowl.

Heat the oil in the wok to 170-175°C. To test the temperature drop in a small amount of batter or a cube of bread, it should float and colour evenly.

Holding the prawns by the tail dip them one at a time into the batter then into the breadcrumbs to coat.

Drop 4 to 5 coated prawns into the hot oil, one by one, and cook for 2 to 3 minutes or until golden brown and crispy. When done remove from the wok with a stainless steel draining spoon or skimming tool onto a warmed metal tray lined with kitchen paper then repeat the batch-cooking with the remaining prawns. Use a splatter guard to prevent oil splashes whilst frying.

Serve the crispy-coated tempura prawns with the sweet chilli sauce and garnish with the coriander.

Cook's Notes

The weight of prawns is measured as fresh and not frozen.

Sushi seasoning is a mixture of vinegar, sugar and salt usually used to flavour cooked sushi rice prior to shaping. Its mix of salt, sweet and sharp flavours make it ideal for the marinade. To make your own, simply mix together 1 tablespoon of rice wine vinegar, 1 tablespoon cater sugar and ½ to ¾ teaspoon salt until the sugar and salt have dissolved.

Panko breadcrumbs are Japanese dried breadcrumbs that are extra crispy; both ingredients can be found in the supermarket.

When frying do not be tempted to cook too many prawns at one time as this will cause a drop in the oil temperature resulting in a greasy coating that will not crisp.