Janssons Frestelse (Jansson’s Temptation) is a classic Swedish Christmas side dish, like fishy potato gratin. It’s traditionally made with ansjovis (often mis-transalted as anchovies by conflation with Dutch) which are actually sprats cured in spiced brine. If you’re lucky enough to be in Europe you can buy these on-line in speciality Scandinavian suppliers. Here in South Africa they’re just not available. However, we do have big bags of frozen sprats in most supermarkets, so I decided to prepare my own ansjovis (see next recipe) just to prepare this dish. Note that Janssons Frestelse is a central part of the Swedish julbord (Christmas smörgåsbord). Rather than 2 x 125g tins of ansjovis, I used half a batch of my own quick-pickled ansjovis (see next recipe).
Prep time: 20 minutes/Cook time 90 minutes/Serves: 4-6
Ingredients:
60g (2¼oz) butter, plus extra for greasing
2 large onions (about 400g [14oz]), thinly sliced
2 tsp sea salt flakes, plus ½ tsp (or 1 tsp fine sea salt, plus ¼ tsp)
1.25kg (2lb 12oz) potatoes, peeled and cut into narrow strips like French fries
freshly-ground black pepper, to taste
225g Swedish ansjovies (pickled sprats) [or 2 x 125g tins, drained], see recipe tip
300ml (1 1/4 cups) full-fat milk
300ml (1 1/4 cups) double (heavy) cream
2–3 tbsp breadcrumbs (optional)
Method:
Preheat your oven to 200C (180C Fan/400F/Gas Mark 6). Butter an ovenproof dish with a capacity of about 2.5 litres (10 cups). Should be about 34 x 20 x 6cm (13½ x 8 x 2½in).
Melt 3 tbsp of the butter in a large frying pan. Add the onions, sprinkle with the ½ tsp of sea salt flakes (or ¼ tsp of fine sea salt) and stir for a few minutes over medium–high heat. Once they start to lose their raw look, turn the heat down to low and cook very gently for 15–20 minutes. Keep an eye on them, and stir regularly: they should be soft and pale gold. If they are beginning to catch, you can sprinkle a little water into the pan, or add more butter. Once they’re ready, use a spatula to scrape them and their buttery juices into a bowl.
Put a third of the potatoes into the buttered dish. Season with 1 teaspoon of sea salt flakes (or ½ teaspoon of fine sea salt) and a generous grinding of pepper. Spread half the soft onions over the potatoes, followed by one tin of sprats. And now layer up again: the second third of potatoes, salt and pepper as before, followed by the remaining onions and the second tin of sprats. Top with the final third of potatoes.
Mix together the milk and cream in a jug and pour it over the potatoes – it won’t cover them completely. Push down any that are poking up, just so that they’re lightly covered with the creamy milk, but don’t worry if they pop up again. Sprinkle over the breadcrumbs, if using, and dot over the remaining tablespoon of butter, then bake for 1 hour, but check at 45 minutes: push a fork in, and if it meets with no resistance, the potatoes are cooked. They’ll certainly be golden on top, but it’s essential they’re soft underneath.
The gratin will stand for a while until needed, and tastes just as good, if not better, warm rather than hot.
