Wikipedia
Kaalan
for the town in Guinea see Kaalan, Guinea
Kaalan is a Keralite ( south India) dish made of yogurt, coconut and one vegetable like nendran plantain or a tuber like yam. It is very thick, which distinguishes it from a similar curry known as pulisheri, and more sour than avial. In many preparations, chillies are also added to make the Kaalan spicy, in addition to its signature sour taste.
Kaalan is typically served as part of the sadhya.