Add coconut, roasted Bengal gram, ginger, garlic, Kashmiri dry red chilies, asafoetida (hing), salt, tamarind paste, and Kashmiri red chilli powder to the jar of a high-speed blender.
Add water and blend to make a smooth chutney.
Heat oil. Add mustard seeds and cumin seeds and let them crackle for 4-5 seconds. Add asafoetida, curry leaves, and dry red chilies and let them crackle for 3-4 seconds. Stir gently while frying.
Pour the tempering over the chutney. Mix well and serve.