Boil pineapple, with turmeric and salt in 1/2 cup water. Grind coconut with dried chilli to a fine paste.
Heat the oil and season with mustard seeds. Saute the coconut paste and add the curry leaves and dried red chillies. When it is done, add the boiled pineapple pieces. The gravy should be thick and the cover the pineapple pieces. Add the crushed mustard just before removing the pachhady from fire.