400 g (13 oz) sea bass fillet, skinned, if you like, and cut into chunks
2 spring onions, sliced
salt and pepper
Heat 1 tablespoon oil in a wok. Add the onion and stir-fry for 2 minutes. Add the ginger, garlic and red pepper and stir-fry for 2 minutes until softened. Mix together the ketchup, vinegar, sugar, soy sauce, 150 ml (1/4 pint) water and the cornflour until smooth. Stir into the wok and cook for 3–5 minutes until thickened. Keep warm.
Fill a large, deep saucepan one-third full with oil and heat until a cube of bread browns in 15 seconds. Beat together the flour, egg and 125 ml (4 fl oz) iced water (don’t worry if there are still a few lumps), then season well. Dip the fish into the batter until coated, shake off any excess and deep-fry in 2 batches for 3–4 minutes until golden brown all over. Drain on kitchen paper.
Stir the fish into the sauce, then serve immediately with the spring onions scattered over.