Cook pineapple pieces along with chilly powder, turmeric powder, green chillies, sugar and salt.
Grind together coconut, cumin seeds and curd.
Once pineapple is cooked and becomes soft, add the coconut paste and cook for 5 - 10 minutes.
Heat oil in a pan or a kadai.
Add mustard seeds and when they splutter, add red chillies and curry leaves.
Pour this seasoning into the above curry.
:- Serve with rice, pulao or biriyani.