I found this in the Time Life Foods of the World Series from 1966 in the volume on India.
Combine the yoghurt and salt in a deep bowl and beat vigorously with a whisk or spoon until the mixture is smooth. Beating constantly, pour in the ice water in a slow, thin stream and continue to beat until all the ingredients are well blended. Taste for seasoning. (A quicker, though hardly traditional, method is to combine the yoghurt, cumin, salt and ice water in the jar on an electric blender and blend at high speed for 1 minute or
We sometimes make our own yogurt here. If anyone is interested I'll aske the yogurt maker to type out the recipe. Donna