Place raspberries, caster sugar, lemon juice and grenadine in a heatproof bowl set over a saucepan of simmering water (don't let bowl touch water). Cover with plastic wrap. Cook, topping up water, for 50 minutes or until deep pink. Set aside.
Warm 1 1/2 cups water and 1/2 cup white wine in a saucepan over low heat. Set aside.
Soften gelatine leaves in cold water for 3 minutes. Squeeze to remove excess water. Add to wine mixture. Whisk.
Strain berry mixture through a fine sieve into a jug. Discard pulp. Add wine mixture. Whisk. Divide among 6 (150ml) glasses. Place in fridge, at an angle, until completely set.
Top with vanilla yoghurt, fresh raspberries and fresh mint leaves.
