Aamsol (आम्सोल) is another name for kokum (Garcinia indica) a plant in the mangosteen family. Aamsol (आम्सोल) is a fruit-bearing tree that has culinary, pharmaceutical, and industrial uses.
All About Kokum | Know Your Spice Amsol or Kokam (Garcinia indica)
Kokum yields a peculiar flavour and deep-red colour. As a souring agent, it is used as an alternative to tamarind in curries and other dishes from south India.
It is also used in cuisine from Gujarat, where it is frequently used to add flavour and tartness to dal (lentil soup) for flavor balance. It is extensively used in Assamese cuisine in many dishes like masor tenga (sour fish curry) and tenga dali (sour dal).