Take one standard-sized coconut. Remove the shell. Keep the coconut water aside. Clean it.
Take a clean grinder.
Cut the coconut into small pieces and put them in the grinder.
Then add 1 tsp of salt to it. (Pro tip: It is good to start with less salt and increase it if needed later on. Remember, if you put it once, there is no way you can take it back).
Add about 1.5 tbsp of lemon juice or of one standard-sized lemon into it.
Now add 1 tbsp of sugar to the content.
Follow it with 2 pieces of fresh green chilies, chopped in small pieces. (Pro tip: 1 green chili will yield about ½ to 1 tsp of chopped chilies. So, I have used about 1 tsp of chopped green chilies. If you the coconut chutney to be spicier, you may add more green chilies).
Finally, add 1 cup of coconut water. The one that you kept aside.
Grind it to a paste.
Now, add ½ cup of dahi (curd) to the paste in the grinder. Blend it nicely.
Check the consistency. You may add some more coconut water according to your liking. (Pro tip: If the grinder cannot grind the content seamlessly, it is good to add more water to the content gradually).
When done, transfer the coconut paste into a bowl. Check the salt. If needed, add some more and mix it nicely.
Now, to prepare the tadka, take a tadka pan and heat it on high flame on your gas stove.
When the pan is hot, pour 1 tbsp of coconut oil into it. (Pro tip: You may use 1 tbsp of white oil such as sunflower oil, peanut oil, and others if you are not fond of coconut oil).
When the oil is hot, put ½ tsp of asafetida in it. (Pro tip: If you prefer gluten-free, make sure you use such a variant available easily in several online and offline stores).
Then put ½ tsp of mustard seeds in the pan as well.
Finally, when the mustard seeds crackle, add 8 to 10 pieces of curry leaves to the content in the pan. (Pro tip: Be careful about the oil sprinkles due to the crackling mustard seeds and also while you put the curry leaves into the pan).
Stir the ingredients continuously to sauté them nicely.
When the ingredients are fried nicely, transfer them to the coconut paste in the bowl.
Mix them nicely.
Your homemade coconut chutney is now ready to be consumed with idli, dosa, and other dishes.