To make cordial you need to pick a shopping bag full of elderflowers. For the most flavour, pick them in the sunshine when the flowers are open and have the most pollen (yellow powder).
You also need sugar, water, lemon juice and citric acid (if you like extra zing and can find it in a local chemist or hardware shop) and sterilised bottles.
You can search online for recipe for exact quantities but I find that approx 2 teaspoons of citric acid are needed for every kilo of sugar. You can use brown sugar but it gives a stronger flavour and darker cordial. I soak flowers for a day in water then strain off the yellowy water, add the sugar and citric acid and bring to the boil. You don’t want to boil the flowers as this scalds them and they turn brown.
Some recipes suggest making a sugar syrup first by boiling the water and sugar and then adding the flowers when it’s cooled down a bit – but then you have to strain the flowers out of a syrup which is messier than straining them out of water.
If you don’t like thunder bugs in your drinks, strain them out through a coffee filter.
If you want to make a lot of cordial to freeze you can cut down the water ratio so it’s more concentrated and takes up less room in the freezer.
I’ve never made elderflower champagne but you can mix the cordial with white wine or sharp cider and fizzy water to get a similar result.
You can also use the cordial to make delicious desserts like sorbets. My Mum even used to make an awesome baked egg custard using elderflower cordial instead of milk.