In a small fry pan heat 2 teaspoon oil. Add ½ teaspoon mustard seeds, ⅛ teaspoon methi/fenugreek seeds and let them splutter.
Add ¼ teaspoon asafoetida and 8-10 dried red chillies. Fry on low flame until the red chillies are crispy and change to a deeper red color. Remove from heat and let it cool down completely.
In a blender first add the tempered ingredients (red chillies, mustard seeds & fenugreek seeds along with the oil) and salt as needed for the chutney. Blend into a not so coarse powder.
Now add ½ cup grated mango and ¼ cup fresh grated coconut. Pulse through a few times until the chutney is blended well. If it is too dry, add a tablespoon of water and not more.
Remove from the blender using dry spoon. It is optional to temper again with mustard seeds.
Store in an airtight container in fridge for upto 3 days. Serve with hot rice, ghee and potato fry.
Notes
Adjust the number of red chillies depending on how sour the mangoes are.
It is important to grind the roasted chillies first else with fresh coconut & raw mango, it will not get blended properly.