Serves 4

This is one of my favourite dishes at the Viet Grill on east London's Kingsland Road, a fantastic Vietnamese restaurant which belongs to my friend, Hieu. It has a kind of sweet and sour taste, but unlike many other sweet and sour numbers, it also has a degree of sophistication, which is due in part to the quality of the fish sauce used. Sometimes, you will also find pork belly added to this dish.

This recipe is very popular in Vietnam and is a typical family dish. The Vietnamese also know how to adapt the strength of the caramelised fish sauce to suit the type of fish they are using. If you can't find catfish – which is available from Asian supermarkets – this works well with any firmer-fleshed fish.

500-600g catfish on the bone, cut into 3-4cm chunks
2-3 tbsp vegetable or corn oil
150g palm sugar, or granulated sugar
60-70ml good-quality fish sauce
1 bunch of spring onions, finely shredded
Medium bird's-eye chillies
Coarse ground black pepper
A few sprigs of coriander to serve

First, make the caramel fish sauce: place half of the oil in a heavy-bottomed saucepan, add the sugar and cook on a low heat, stirring until the sugar has dissolved; continue cooking on a low heat and stirring every so often until the sugar begins to colour, then remove from the heat and stir in the fish sauce and about 150ml water. Transfer to a clay cooking pot or similar.

Clean out the pan and heat the rest of the oil with the spring onion and chilli for about a minute. Drain the oil into the caramel, add the chunks of catfish and leave to marinade for 1-2 hours.

To serve, bring the liquid and fish to the boil, cover with a lid and cook on a medium flame or in a moderately hot oven for about 40 minutes.

Add a good half a tablespoon of ground black pepper and serve with some sprigs of coriander scattered on top.