1 l stripped blackcurrants
200 ml water
sugar (for quantity, see instructions below)

Rinse the berries quickly, strain and shake off the excess water. Pour the berries in a saucepan with the water.

Crush the berries slightly. Bring the mixture to the boil and simmer on low heat for about 10 to 15 minutes.

Place a large, round colander on top of a clean large measuring cup or a saucepan. Line the colander with a clean cheesecloth rinsed with boiling water. Pour the berry mixture in the colander and let stand without stirring for about half an hour, until all the juices have dripped in the cup or saucepan below.

Measure the juice and bring it slowly to the boil in a saucepan. Start adding the sugar little at a time, using 450 millilitres of sugar for every 500 millilitres of juice. Keep adding the sugar slowly, stirring until it melts. Let the mixture simmer, uncovered and without stirring, on a low heat for about 10 to 20 minutes. During cooking, carefully skim any foam forming on the surface with a slotted spoon.

Test the jelly to see whether it is ready for canning: pour a little jelly on a chilled, small plate and let it cool for a while. (You may place the plate in refrigerator for a couple of minutes.) Then draw your finger or a spoon across the jelly  —  if it leaves a clear path and does not run, it is ready for canning. If it is still very runny, continue cooking for a couple of minutes longer  —  yet no longer than 30 minutes in all.

Take the saucepan off the heat and let the jelly mixture stand for a couple of minutes. Then pour the hot jelly in hot jars sterilized with boiling water. Close with sterilized lids and let cool.

Store the jelly in refrigerator. Serve it as an accompaniment for roasted meat and game dishes or to flavour sauces, cake fillings and desserts.

Note:
Sometimes when cooking jellies, they will not set, but remain runny, no matter how long you let them cook. This happens because the fruit or berries used do not contain enough pectin. If a jelly made according to this recipe will still not set after it has been cooked for 30 minutes, some commercial fruit pectin should be added to it. In this case, follow the instructions in the pectin package.

Also jam sugar, already containing added fruit pectin, may be used instead of regular sugar. For quantities and cooking time, follow the instructions in the jam sugar package.

Recipe source: traditional Finnish recipe.