The flowers of the Elder tree can be used to make cordial but I prefer to wait until the tree has developed berries and they have turned black before I harvest to make jam. Forraged fruit gives a more complex flavour than that of usual berries.
Picking the tiny berries off the tree and de-stalking the fruit takes time but it is worth the effort.
Fruit with minimal of no pips generally lack pectin so you need to use jam sugar or the pith of a lemon will work also to set the jam (it is the pith in fruit that contains pectin).
The normal recipe for jam making is equal quantities to fruit to sugar, so weigh the fruit and add to the pan and then add the same weight in jam sugar. 1-2 lemons should be sufficient to set the jam without making it too sharp.
Boil the jam until the temperature reaches 105c and continue for a further 10minutes, if you don’t have a jam thermometer when the jam coats the back of the spoon, or use the wrinkle test (where a spoonful of jam is placed on a place in the fridge to cool, push with a finger and if it wrinkles it is set).
Spoon off any scum from the jam and put into warm sterile pots, seal and store in a cool dry place.