I should say this is an 'Elixir of life' during summer. i have seen in village sides of Tamilnadu serve this as a 'welcome drink' to the guests. It can be consumed by diluting yogurt with water and adding a pinch of salt or by adding certain ingredients to make it tastier.
here we go,
A piece of ginger
A pinch of hing
A small piece of green chilli
Salt to taste(Kal uppu is best for this)
1) Squeeze corriander leaves, curry leaves. ginger, green chilli's, little salt by using motor & pestle, or by hands if comfortable and extract the juice.
2) Beat the yogurt with a pinch of hing, required amount of salt and dilute it.
3) Add the extracted juice (can also add the crushed mixture,however, most of them do not like the leaves on mouth while drinking) to the diluted yogurt.