Masala Chaas or Spiced buttermilk is a rustic traditional summer refreshing low fat healthy made out of yoghurt which is subtly spiced with some chat masala, cumin, black salt and a few herbs.
You can season it with mustard seeds and asafoetida (hing) if you prefer.
Mint, coriander, small piece of onion, chopped cucumber, Lime leaves, cumin a pinch can be added to flavour this.
To make the yogurt less sour, add in a little milk while making Chaas.
Buttermilk can also be substituted for the yogurt and water.(Like how I have prepared)