KO EN Swedish Side dish⏱ 95 minEdit history

Janssons Frestelse (Potato and Sprat Gratin)

Name: Janssons Frestelse (Potato and Sprat Gratin)
Prep time: 30 min
Cook time: 1 h 5 min
Total time: 1 h 35 min
Yield: 6 servings
Cuisine: Swedish
Ingredients: 1 kg potatoes; 2 onions; 125 g Swedish ansjovis (sprats in a sugar and spice cure); 300 ml double cream; 100 ml milk; 40 g butter; 3 tbsp breadcrumbs; 0.25 tsp white pepper; salt

Sweden's potato gratin: matchstick potatoes and onions softened in butter, layered with Swedish ansjovis, covered in cream and baked under breadcrumbs. The ansjovis on the label is not an anchovy but sprat in a cure of sugar and spice, so the seasoning of the whole dish comes out of one tin rather than a salt cellar — salt, sweetness and spice at once.

Ingredients

6servings

potatoes · floury or all-purpose1 kg
onions · thinly sliced2
Swedish ansjovis (sprats in a sugar and spice cure) · one tin, brine included; Scandinavian grocers125 g
double cream300 ml
milk100 ml
butter · for the onions, the dish and the top40 g
breadcrumbs3 tbsp
white pepper0.25 tsp
salt · none at first; only after tasting the brine

Steps

Heat the oven to 200°C and butter a 1.5-2L baking dish.
Soften the onions in 15g of the butter over low heat for 10 minutes, until translucent and soft but not coloured.
⏲ 10 min
Peel the potatoes and cut them into 5mm matchsticks. Do not rinse them — the starch on the cut faces is what holds the cream.
Lay half the potatoes in the dish, spread the onions over them, scatter the sprat fillets evenly and cover with the rest of the potatoes. Grind over the pepper.
⏲ 5 min
Mix the cream and milk, stir in 2-3 tablespoons of brine from the tin and taste it. Add salt only if it needs it. Pour on half, scatter the breadcrumbs, dot with the rest of the butter and bake for 30 minutes.
⏲ 30 min
Pour the rest of the cream in around the edges and bake 20-25 minutes more, until a knife meets no resistance in the potatoes and the top is deep gold.
⏲ 25 min
Let it stand 10 minutes before serving, while the cream settles between the potatoes.
⏲ 10 min

Tips & Variations

Variations

With Italian anchovies only: halve the amount (50-60g), and in place of the brine put a pinch of sugar and a pinch of ground allspice into the cream. The saltiness comes out close; the aroma does not, and you are making a different dish knowingly.
Baltic spiced sprats: the spiced sprats sold in Estonia and Latvia are the same family of cure and swap in directly.
Sliced potatoes: thin slices work in place of matchsticks. With less cut surface the cream is looser, and there are no ends poking up to crisp. The matchsticks in the photograph are the dish's usual shape.
Where it sits on the table: it is fixed on the Christmas buffet (julbord) and turns up at Easter and midsummer too. Mostly a side, and also something reheated late at night at the end of a party.

Tips

The ansjovis on the label is not an anchovy. Bagnun sorts anchovies as a salted condiment meant to melt away, and gives the reason: "Salt curing has already broken the protein down, which is why it melts." Swedish ansjovis is not that salt cure. It is sprat cured in sugar and spice — the direction haring describes for Swedish herring, "a sweet cure with sugar and spices", and calls a different dish. Translate a recipe and swap in anchovies, and you get a saltier, unsweet, different dish.
The seasoning comes out of one tin. Gratin dauphinois says "Dissolve the salt in the cream." Here the brine from the tin is that salt. It carries sugar and spice dissolved in it as well, so the moment it goes into the cream the salt, the sweetness and the aroma spread together. That is why salt goes in only after tasting the brine.
Do not rinse the potatoes — for dauphinois's reason. With no flour or cheese, dauphinois says, "potato starch is the only thing holding the cream". The same holds here, and matchsticks have more cut faces than slices, so more starch comes off to hold it.
Pour the cream in two goes. All of it at the start and the potatoes sit submerged and boil, and the top is slow to dry. Start with half, let the crumb crust form, then pour the rest in around the edges.
Do not colour the onions. The sweetness of browned onion piles on top of the ansjovis's own and the dish goes heavy. Cook them translucent and let them add softness only.
Scatter the sprats evenly. Clustered, they make one corner salty. The flesh is soft and half dissolves into the cream as it bakes, and what dissolves is what seasons the rest.