"Amchur" is a Hindi word that refers to a tangy and sour powder made from dried green mangoes. It is commonly used as a spice in Indian cuisine to add a sour taste to dishes, similar to how lemon or vinegar does. Full definition
(if you are using lemon juice instead of amchur powder, sprinkle it over the aloo masala now). (happyandharried.com)
Tip in the mashed potatoes, season with salt and add amchur powder. (happyandharried.com)
Pairing the bitter melon with tangy amchur (green mango) powder, sweet coconut palm sugar, and a generous amount of spices also help balance the overall flavor. (thedomesticman.com)