Soak the elderflower umbels unwashed in 1.5 liters of cold water for about 1 hour and collect any beetles from the surface of the water. (Original comment from my great-grandmother.)
Skim off the flower umbels, pluck the flowers from the stems (I use scissors) and put them back into the water. Let simmer for 45 minutes.
Pass the flower water through a fine sieve to separate the flowers from the liquid. Then pour again through a sieve lined with linen (I`ll use a household roll).
Reduce the liquid to about 450 ml while simmering, allow to cool. Top up the reduction with grape juice, lemon juice and red wine. Mix the liquid with 1 kg of preserving sugar 1: 1 and cook for about 5-6 minutes.
Pour the boiling hot jelly into prepared jars, close and place on the lid for about 2 minutes. Then let it cool down.
Getting the reduction to exactly 450 ml is a bit difficult. I fill up with grape juice or red wine if it isn`t enough. It is important to bring the total liquid to about 750 ml.