Heat a kadai and add the oil.
Add the potato and onion pieces and sautT well, add some water .
Cook the potato and onion pieces on low flame with a closed lid
Take another frying pan and fry the grated coconut, coriander seeds and red chillies, till brown.
Make a thick paste by grinding all the fried ingredients (use a little water).
Add the ground coconut paste to the cooked potato.
Pour 1 cup water and add salt then stir it well.
Heat oil in a kadai and splutter mustard seeds and curry leaves.
Cook for 10 minutes on low flame till the gravy thickens.