Food: First catch your anchovies

Annie Bell will go to any lengths for a Swedish-style Sunday supper. Photograph by Patrice de Villiers

It began with the most innocent of conversations, the kind of chat you have with your editor that goes "how about something easy, Sunday- nightish and delicious?" I don't think either of us envisaged it would end up in Lakeside Thurrock with what were to prove probably the most expensive anchovies in the world.

Jansson's Temptation is one of my all-time favourite potato dishes. You may be familiar with this gratin that layers potatoes, sliced a little thicker than a matchstick, with onions and anchovies, before being smothered in cream and baked until the potato underneath is meltingly tender, and that on top is golden and crisp, while the anchovies fuse with the cream into a wonderful salty sauce.

I have been making this for years. It is like a Spanish omelette, in that, when all else fails and the cupboard is almost bare, there is usually still the necessary to assemble it, and it takes all of 20 minutes to throw it together. When I cooked it the other night, my mother and I managed to consume almost the whole of a dish intended for four, which is the kind of thing you live to regret - it is deceptively rich.

Mr Jansson, however, is the Lord Lucan of the cookery world. He is, or was, Swedish - that much is fact. Beyond this, his name changes from Janssen to Janeson to Jonsson to Janzon, followed up by "frestelse", Swedish for temptation. He was "a religious enthusiast who emigrated to the United States in the 19th century and founded a colony of disciples in Illinois who forbade eating for pleasure, but he succumbed to this dish" (Alan Davidson, North Atlantic Seafood). He has also been incarnated as a chef at a hotel in Sweden earlier this century (Lotte Karlsson, chef at Fiske restaurant in Upper Street, Islington). Elsewhere, he has been cited as a gourmet opera singer who would tempt his friends after his performances with this late-night snack. And, most banal of all, the dish is alleged to be named after a film.

As to his Christian name, it is sometimes Pelle, sometimes Erik and sometimes Adolf. Whatever the truth, Mr Jansson in culinary mythology or Mr Janson in real life was on to a very good thing.

But the temptation that we have succumbed to over here bears little relation to the real one. After all, when we use anchovies we look to the feisty little fillets of Italy, filetti di acciughe, that instantly invade with their sweet pungency, salty, aromatic and concentrated. The finest are lusciously pink and plump, ripened on a bed of rock salt, and, authentic or otherwise, they make a fine Jansson's Temptation.

This anchovy frequents the warm waters of the Mediterranean. It is small and blueish-green with a silver belly, and it tends to the deep water. But it is not only the Italians who value it as a seasoning: it appears as fish sauce in the Orient, as anchovy essence, or hot-smoked in the Soviet Union. But only occasionally, does it venture as far north as the freezing waters of Denmark.

Swedish anchovies are not anchovies at all, they are sprats, or what we most commonly eat as whitebait when they are fried. These, too, are small, silver-bellied and blueish-green on the sides, not unlike their Italian equivalent. But their fate is a spicier one, and sweet rather than salty: they are layered in a barrel with sugar and numerous aromatics, where they lie for three to four months before being filleted. Many years ago, the Swedes named this product ansjovis, or anchovy.

But where to buy them? Swedish delis and restaurants do not abound in quite the same way as Italian. Sweden's most famous export is IKEA and this, indeed, is where I eventually tracked them down. Not in the impossible- to-reach Brent Cross one on the North Circular, but in the even-more-impossible- to-reach Lakeside Thurrock one on the M25.

Please don't go rushing off to buy yourself a tin; I have done the tasting for you and can report they are like a rollmop herring only the size and shape of an anchovy fillet. In any case, I picked up the last two tins available in the country until the next shipment arrives. One is pictured here, the other I made into an authentic Jansson's Temptation that was sweeter than the Italian-inspired one, with overtones of juniper, cloves and star-anise. But as the anchovies were couriered from Lakeside Thurrock at a cost of about pounds 5 per fillet, I reckon they are probably the most expensive anchovies in the world.

Jansson's Temptation, serves 4

1 Spanish onion

900g/2 Ib waxy potatoes

15g/12 oz unsalted butter

15 salted anchovies

275ml/10 fl oz double cream

150ml/5 fl oz vegetable stock

black peppers

Preheat the oven to 200C (fan oven) /220C (electric oven)/425F/Gas 7. Peel the onion, halve and finely slice into half moons. Peel the potatoes and cut these into very thin chips (this is the most irksome part of the recipe but it's really worth it). First slice them, then arrange several slices on top of each other and chip them.

Grease the dish with butter - it should a gratin dish of a size to hold the potatoes and onion to a depth of about 5cm/2in. Lay half the potatoes on the base and scatter over the onions, then lay the anchovy fillets on top and arrange the remaining potatoes on top of these. Press them down with your hand, mix together the cream and vegetable stock, season with pepper and pour this over the potatoes, The liquid should cover them by about half. Spoon 2 teaspoons of the anchovy oil over the potatoes. Cover with foil and bake for 30 minutes, then remove the foil and cook for another 20-25 minutes until the top chips are golden and crisp, and those underneath are lovely and tender

My favourite Italian anchovies come from Carluccio's, and these can now be obtained by mail order. For a real treat, order yourself the kilner jar of them (0171-240 5710). Swedish anchovies are normally available from IKEA