2 tablespoons Apple Cider Vinegar (or White Wine Vinegar)
Instructions
Add sugar and water and stir till the sugar is dissolved
Add the elderflower heads, lemon, vinegar and yeast
Cover with a muslin cloth (to allow air out, but no bugs in)
Elderflower heads should have enough natural yeast on them to get themselves going. If after 24 hours there doesn't seem to be any fermentation (no bubbles) add a teaspoon of bread, champagne or white wine yeast.
Leave to ferment a further 4 days, then lay the muslin inside your regular sieve and pour the liquid out so that it catches all the plant matter in the sieve. This is where I pour it into the demijohn and place the bulb into the cork.
Put some water into the bulbs - this allows the gas to escape but doesn't let air in and leave for 3 - 4 days while it ferments further.
From here, add a half teaspoon fine white sugar to your 500ml bottles, and decant the champagne into individual bottles. Check from time to time so that they don't explode, but set aside for 2 weeks.
Chill before serving - there may be sediment at the bottom of the bottle, so don't pour it out all the way.