20 elderflower heads (This is more than in most recipes, so reduce if you find elderflowers a little overpowering)
150ml white grape juice concentrate
3 lemons, washed
1 Champagne yeast
4.5 litres of boiled water cooled to room temperature
You only need the florets themselves (too much stalk can add an unwanted bitterness to the brew). Remove them with a fork.
Put them in a sterilised bucket and thoroughly mix in the sugar. Leave for about three hours to extract the flavour. Add the water and stir until the sugar has dissolved. Add the grape concentrate, yeast and yeast nutrient. Halve and squeeze the lemons, then throw in the peel as well. Stir.
Cover the bucket and leave for up to a week, stirring occasionally for the first three or four days. Siphon into a sterilised demi-john and add an airlock. The liquor will still be sweet and has quite a bit of fermenting to go. The bubbles in the airlock will appear at about one per second.
This will slow down after one or two weeks and this is the time to test your brew with your "hydrometer". It measures the specific gravity of the liquor, which in turn gives a good indication of the amount of sugar remaining. Remove the airlock and carefully drop in a sterilised hydrometer. It should read "1010". If not, then replace the airlock and leave your brew a bit longer.
Once the magic number has been achieved, siphon off into champagne-style bottles, fit new corks (plastic "corks" are the easiest) and a little wire cage to prevent accidents.
Leave for several weeks at room temperature to allow the fermentation to add fizz to the wine. A sediment will form at the bottom of the bottles. This is normal and commercial producers of sparkling wines go to great and complex lengths to remove it. At home it is easiest to cool the bottle in the fridge then decant carefully into a chilled jug just before serving.