Keri Nu Khatu Athanu, or mango sour pickle, is a traditional Gujarati pickle made from ripe mangoes. The mangoes are sliced and marinated in a mixture of spices, including salt, chili powder, turmeric, fenugreek seeds, and mustard seeds. The pickle is then left to ferment for a few days, allowing the flavors to develop and the mangoes to become tangy and sour. Keri Nu Khatu Athanu is known for its bold and tangy taste, and it pairs well with Indian meals, adding a zesty kick to rice, dal, or curries.