Lassis are a yoghurt drink originating from the northern state of Punjab. A perfect blend of yoghurt, water, salt or sugar and sometimes spices, blended until frothy.
In India they churn it but you can use a blender or whisk. I love mine sweetened with fruit, which is a modern version. Traditionally they are sweetened with sugar syrup or delicately salted. And the best to be had is on the streets of Amritsar.