Peel and dice the mango or open the can and pour off the water. Puree with the buttermilk and season with a squeeze of lemon, a little vanilla and sugar.
Fill into glasses and add a few berries, e.g., Blackberries, garnish.
Lassi has the name for Germans because in India this drink is usually made with yoghurt and water and buttermilk is rather untypical.