Pressure-cook or steam-cook the cob pieces in a microwave until tender.
Chop the onion very finely.
Heat oil in a non-stick pan and add the mustard seeds. When they pop, add the cumin seeds and fry for 30 seconds.
Add the pepper flakes and curry leaves.
Add the chopped onion and fry until golden brown.
Add turmeric, then coconut milk, yoghurt, salt and chilli powder. Mix thoroughly and bring to boil.
Add the steamed cob pieces and continue to boil until the mixture is reduced to a thick gravy. Stir constantly and keep turning the cobs so they are evenly coated with the gravy throughout the cooking.
Serve with rice or use as a filling for sandwiches.