Food & Drink: Cold fish rise to a Latin passion: South American marinades bring the sharpness of citrus and heat of spice to fresh, raw seafood

One of the most surprising dishes I tasted in Ecuador was a ceviche of conchas, a marinade of conches, in the seaside town of Bahia de Caraquez. It was the last stop on our journey up the coast from the grim city of Guayaquil, before turning inland to drive back up to the heights of the Andes. Along the way, we had watched fishermen casting their nets and sorting their catch in the early morning before the sun began to breathe fire.

We had eaten good fish, simply cooked, and a couple of not very inspiring ceviches of tasteless prawns. At Bahia de Caraquez, we decided to give the ceviche a last chance. What arrived looked funereal. The Ecuadorian conch, black-fleshed and meaty, has a superb flavour: this one's marinade had taken on a correspondingly muddy colour from its juice. But, colour notwithstanding, we polished it off and ordered another - a ceviche to remember.

Ceviche, fundamentally no more than raw seafood marinated in lime, lemon or Seville orange juice, is a South American coastal speciality. Different countries have their variations on the theme: local fish, special accompaniments, particular additions to the citrus marinade.

Whatever the location, the principle remains unchanged. This is a way of extending the shelf-life of fresh fish in a hot climate where refrigeration was, and often still is, rare or non-existent.

The citrus juice plays a multiple role. As well as a preserver, it changes the nature of the substance, coagulating the proteins in much the same way as heat does. In effect, it cooks the raw fish but leaves the freshness of flavour unaffected. Last, but by no means least, it adds the sharpness that fish so often needs.

Very fresh fish is essential. There is no point in making a ceviche with tired fillets of whatever the fishmonger is trying to sell off cheap. Half the flavour is already lost and, of course, without the sanitising effects of cooking, you risk stomach upsets. Not worth it.

Most fish take well to the ceviche, and freshness matters more than variety. You probably will not be using the same fish as in the country of origin, anyway. I have made suggestions in the recipes that follow, but most white fish will do (cod, sole, halibut or sea bream, for instance). Salmon takes well to the plainer ceviches and scallops are delicious.

Marinated raw fish is at its best within a few hours of preparation; just how many is a matter of debate. The thinner you slice the fish, the quicker it 'cooks'. The marinade starts work instantly - you can see its effect within minutes. Sliced fish, 1/4 in (1/2 cm) thick, will be 'done' within half an hour. Double the thickness and

1-1 1/2 hours should suffice. A few hours sitting around, covered, in the fridge is fine; but after that it becomes over-sharpened, which dulls the flavour of the fish, and the texture suffers, too.

Scallop ceviche

A simple classic that brings out the sweetness of fresh scallops. It works well with any white fish, and even salmon takes to it. Vary the salad vegetables as the fancy takes you.

Serves 4

Ingredients: 8 large scallops

juice of 3 limes or 2 lemons

1 thin red chilli, or 1 green chilli, deseeded and finely chopped

4 spring onions, thinly sliced

1 generous tbs chopped coriander leaves

1 avocado

1 green pepper, thinly sliced

8oz (225g) tomatoes, deseeded and diced

2-3tbs olive oil

salt and pepper

Preparation: Separate whites and corals of the scallops. Slice each scallop white into 3 discs. Marinate whites and corals with about two-thirds of the lime or lemon juice for 1/2-2 hours.

Shortly before serving, peel and remove the stone of the avocado. Slice thinly, turning in a little of the remaining lime or lemon juice to prevent browning. Drain the scallops and mix with the chilli, spring onions and coriander. Arrange avocado slices and green pepper on one large serving dish, or four individual ones, with the scallops in the centre. Scatter with diced tomato and drizzle over the olive oil, then season with salt and pepper and serve.

Ecuadorean ceviche

The incongruous ingredient in this recipe is tomato ketchup - I did not believe it at first, but in the end I overcame my apprehensions and tried it. Plenty of lime juice tames the taste and it really does not ruin the fish. It is unusual, very good, and well worth trying.

Note, too, the marinated onions, cebollas encurtidas, which are used as a relish with many Ecuadorean foods and can be stored in the fridge for several days.

Serves 4

Ingredients: 8oz red onions, very thinly sliced

2tbs salt

juice of 4 limes

pinch of sugar

1lb (450g) freshest cod fillet

3 1/2 tbs tomato ketchup

1 thin red or green chilli, deseeded and finely chopped

2tbs chopped coriander leaves

salt and pepper

To serve:

1 avocado

salted popcorn (optional)

Preparation: Rinse the onions in cold water and drain. Mix with the salt and leave for 20 minutes. Rinse again thoroughly under the cold tap. Mix with the juice of 1 lime and the sugar, then leave for a good half-hour before using.

Cut the fish into strips about 1/2 in (1cm) wide. Place in a shallow dish and pour over the remaining lime juice. Leave for 1/2-2 hours.

Drain the juice from the fish and mix with the tomato ketchup. Pour back over the fish and add the chilli, half the onions, coriander, salt and pepper. Mix carefully and divide between four dishes, then top with the remaining onions. Just before serving, slice the avocado and arrange with the marinaded fish on the plates. Serve at once, with separate bowls of popcorn if you wish.

Kokoda

This 'ceviche' from Papua New Guinea begins much as any other. The difference lies in the final dousing of coconut milk, coloured and flavoured with turmeric. If you use tiny, thin red chillies, then two will be called for. Last time I made this, though, I used just half one of those ferocious Scotch Bonnet chillies, and it was quite hot enough.

Serves 4-6 as a first course

Ingredients: 1 1/2 lb (675g) fillet of firm white fish such as cod, monkfish or sole, skinned

4 limes

2 red chillies, deseeded and thinly sliced

1/2 tsp turmeric

1/2 in piece root ginger, grated

8fl oz (230ml) coconut milk

salt

To serve:

lettuce leaves, shredded

Preparation: Cut the fish into strips about 1/2 in (1cm) thick, carefully removing all bones, and spread out in a shallow dish. Pare the zest from 1 lime, shred and blanch in boiling water for 1 minute. Drain, cool and keep covered until needed. Squeeze the juice from all 4 limes and mix with the grated ginger and half the chilli. Pour over the fish. Cover and leave in the fridge for 2-8 hours, turning occasionally.

Warm the coconut milk with the turmeric and salt, stirring until turmeric has fully dissolved. Cool. Half an hour before serving, drain the marinade from the fish and pour over the coconut dressing. Scatter with lime zest and remaining chilli and serve on a bed of lettuce.