Mix the raspberries, sugar, 6 tablespoons of water and 2 tablespoons of lime juice in a saucepan. Bring the whole thing to the boil and cook for 15 minutes over a mild heat. Place the cooked raspberries in a sieve lined with a damp cheesecloth, drain thoroughly and collect the juice (approx. 250 ml) in a bowl. Squeeze out the cheesecloth well.
Cut the organic lime into 8 thin slices and distribute between 8 champagne glasses. Top up with cold sparkling wine, prosecco or champagne and 3 - 4 tablespoons of raspberry syrup. Tip: 2 - 3 fresh raspberries per glass give the whole thing a kick of freshness.