prepare coconut milk from the freshly grated coconut by grinding it in the mixer without adding water you may get 1/2 to 3/4 cup of milk; if not much,dont worry, keep first milk aside.
grind it again adding 1 cup tea cup hot water and squeeze ,this is called second milk.
cut onion ,potato as long pieces same as for sambar. cut ginger like matchbox sticks. split green chilly vertically put all these ingredients into a cooking vessel ,add 1/2 cup water salt to taste to it then boil until potato cooks dont smash them.when potatoes almost cooked add second milk when it comes to a boil (dont boil too much) add first milk stir well, add curry leaves then switch off the heat(no need to boil just heat).then add coconut oil ,stir well and close with a lid. Now stew is ready.if you want you can add 1/2 tsp of sugar.