Put the rhubarb, the rhubarb syrup, sugar, stem ginger and 1 tbsp water in a small pan and bring to a gentle simmer, breaking up the rhubarb with a back of a spoon. Remove from the heat and leave to infuse for 1 hr. Strain into a jug, pressing the rhubarb through to release all the juice. Discard the solids and leave to cool completely. Will keep, chilled, for up to two days.

Put 1 tbsp of the prepared rhubarb ginger syrup into the bottom of four champagne flutes. Divide the lime juice between the glasses, about 1 tsp each. Add the non alcoholic rhubarb & ginger flavour gin to each glass and stir with a bar spoon or teaspoon. Top the flutes up with the chilled nosecco and put a piece of crystallised ginger onto the side of each glass to serve.