In Sweden and Finland alike, "Jansson's temptation" is a popular late night dish, a salty snack that can be served for friends and guests after a night out, for example on New Year's Eve. It is often served as a part of smörgåsbord buffet meal.

To obtain its characteristic flavour, the dish must be made solely using Swedish anchovy fillets. Read more about them here.

1 medium or large onion
at least 500 g floury potatoes
1 can (125 g/81 g) of Swedish anchovy fillets
about 200 - 250 ml cream
pinch of white pepper
butter

Peel the onion and cut in quarters. Slice the quarters thinly and sauté in butter until soft, translucent and golden. Do not let them brown. Set aside.

Peel the potatoes and cut them into 5 × 5 mm wide julienne strips. This is most easily done using a food processor's slicing/shredding attachment fitted with a julienne disk, a mandoline, or another slicing device. Make sure you have about 500 grams of potato strips.

You may plunge the potato strips briefly into cold water to remove some of the starch if you like. This prevents the potato pieces from sticking together too much while the dish is cooking. Drain the strips thoroughly.

Open the can of anchovy fillets and drain them, reserving the canning liquid. Layer the potato strips, anchovies and onion slices in a buttered, shallow casserole dish, starting and ending with a potato layer.

Take half of the cream and mix in it 2 tablespoons of the reserved anchovy canning liquid and some freshly ground white pepper. Pour the mixture over the ingredients in the casserole dish. Dot the surface with pats of butter. Bake at 200 °C for about 30 - 35 minutes.

Take the dish out and pour over the rest of the cream. Then bake for a further 15 to 30 minutes. Note that you may not need to add all of the cream if the dish still seems very moist and watery. On the other hand, you may need to add even more cream if the dish has started to dry out too much.

This all depends mostly on the size and depth of the dish you are using  —  from a shallow dish the liquid evaporates quicker than from a deep dish. Ideally, use a fairly shallow dish, so that the gratin will not remain soggy. Keep checking the consistency every now and then during baking, especially when preparing this dish for the first time.

Take the gratin out when it has nicely browned on top and the consistency is creamy, not watery. Serve with fresh, sliced cucumber or gherkins or fresh, mixed salad.

For a slightly lighter version of this dish, replace half of the cream with milk or beer. Also, if you like a stronger onion flavour, do not sauté the onion before adding it to the dish.

Recipe source: traditional Swedish recipe.