Without a doubt the easiest way to obtain lingonberry jam outside the Nordic countries is to buy it from your nearest IKEA store (surprisingly, they do sell a pretty good tasting brand).
Nevertheless, here is a recipe for a homemade jam, if you happen to have lingonberries at hand.
fresh or frozen lingonberries
for quantities, see instructions below
Weigh the lingonberries. If you are using fresh berries, see that they are all ripe (= bright red in colour), whole and dry. Discard any white coloured berries (they are unripe). If you are using frozen berries, do not thaw them beforehand.
Measure the sugar and water use between 500 grams to 1 kilogram of sugar for every 1 kilogram of berries and 300 millilitres of water for every 1 kilogram of sugar.
Pour the sugar and water in a thick-bottomed, wide and large saucepan. Bring the mixture to the boil and cook on low heat until clear and syrupy. The sugar syrup should form a thin "thread" when dropped from a spoon. Skim any foam forming on the surface with a slotted spoon.
After the sugar syrup has cooled down a bit, add the fresh or frozen berries. If you are using frozen berries, the mixture is likely to seize up into a clump, but it will dissolve as soon as the mixture is slowly heated and the berries will start to thaw.
Do not stir the mixture, but only gently shake the pan for the berries and the sugar syrup to mix.
Bring the mixture rapidly to the boil, shaking the pan every now and then. Then lower the heat and let the mixture boil for three minutes exactly. During this time, carefully skim any foam forming on the surface with a slotted spoon. Take the pan from the stove, shake it and leave to stand for 10 to 15 minutes.
Skim any possible foam.
Place the pan back on the hot stove, bring the mixture rapidly to the boil again and cook for another three minutes, skimming the foam. Then leave the mixture to cool again.
Repeat the 3-minute boiling and cooling process until the jam is clear, ie no more foam is rising on the surface of the jam, and the berries are dark and translucent. But be careful not to cook the jam for too long or it will become too thick and marmalade-like.
Pour the hot jam in hot jars sterilized with boiling water. Close with sterilized lids and let cool. Store the jam in refrigerator.
Like any jam, lingonberry jam may be served with porridges or desserts like pancakes, ice cream, cheesecakes etc. But in Finland and Sweden, it is also served with many savoury dishes like liver hamburgers, liver casserole, meatballs, stuffed cabbage rolls, Wallenberg steaks or reindeer stew.
Recipe source: family recipe.