Let the elderflower soak in alcohol and wine for 2-3 days, pass through a fine sieve with a cloth, squeezing out the soaked flowers a little. Add lemon juice.
Continue working with the 800g sugar as instructed by Gelfix, bring the liquid to the boil while stirring constantly, making sure that any lumps are completely loosened by crushing.
Fill twist-off glasses while still hot and place on top / lid for 5 minutes.