1 - Mix the cornflour and 1 tbsp soy sauce, toss in the prawns and set aside for 10 mins.

2 - Stir the vinegar, remaining soy sauce, tomato purée, sugar and 2 tbsp water together to make a sauce.

3 - When you’re ready to cook, heat a large frying pan or wok until very hot, then add 1 tbsp oil.

4 - Fry the prawns until they are golden in places and have opened out– then tip them out of the pan.

5 - Heat the remaining oil and add the peanuts, chillies and water chestnuts.