Half a kg of fresh or frozen blueberries with about two cups sugar and, oh, let's say about half a cup of lime. If you have orange liqour add a half cup of that too, but that's optional. Throw all into a saucepan, add a little water and bring to a boil. Then lower heat and let simmer with lots of stirring. If there's any froth on the top, keep removing it with a spoon. Test if the jam set by letting a spoonful cool on a metal spoon and see if it's thick enough to form a layer. Take off the heat immediately once it's set, and spoon into a clean, dry jar. Seal!
