Method
Sea Buckthorn sauce: cook 125g sea buckthorn berries gently with 1 tsp maple syrup for 30 mins until very soft. Press through sieve, add 120g sugar, simmer 5 mins. Cool and store in fridge. Granita (serves 4): mix 180ml sea buckthorn sauce, 700ml prosecco and 100ml Aperol. Pour into a shallow freezer-proof container and freeze. Every 30 mins fork through the mixture until slushy and granular (about 3 hours). Serve in chilled glasses.