Mix yogurt, water and blend well. Temper curry leaves, mustard seeds and asafoetida in a thick pan without oil and add it to butter milk. Season with sea salt.
Variations
Buttermilk can be made with other plant-based yogurts.
The flavorings can vary according to your preference, for example roasted cumin powder, ginger chili paste, mint and coriander, roasted whole cumin and asafoetida.