500g rhubarb (about 1 large bunch), trimmed, cut into 1cm slices
2 thick strips lemon zest
Juice of 1 lemon
1 1/2 cups (330g) caster sugar
1 vanilla bean, split and scraped (or 1 tbs vanilla bean paste)
1 tsp citric acid
2 tsp rosewater
Floral ice cubes (see method) and chilled sparkling water or prosecco (substitute dry sparkling wine), to serve
To make the floral ice cubes, you’ll need edible flowers or petals (such as pansies, viola, borage, rose, dianthus or chamomile – be sure to only use organic, unsprayed, food-grade flowers). Half-fill some ice-cube trays with cooled boiled water. Gently place edible flowers or petals into each hole of the trays. Freeze for 2 hours or until frozen. When frozen, top up the trays with extra cooled boiled water and return to the freezer for a further 2 hours or until frozen.
To make the cordial, place rhubarb, 350ml water and lemon strips in a large saucepan and cover with a lid. Bring to the boil over high heat. Partially remove lid and simmer, stirring occasionally, for a further 10 minutes or until fruit is very soft.
Tip fruit mixture into a sieve lined with a piece of clean muslin set over a heatproof jug or bowl. Allow to strain for at least 2 hours. Discard pulp and pour strained liquid into a saucepan. Add lemon juice, sugar, vanilla pod and seeds (or paste). Cook over medium heat, stirring, until sugar dissolves. Remove pan from heat. Gently whisk in citric acid and rosewater.
Discard vanilla pod and pour hot cordial into a sterilised glass bottle or jar. Seal and allow to cool to room temperature. Place floral ice cubes in serving glasses, pour over cordial and top up with sparkling water or prosecco. Serve.