Grind coconut , turmeric powder and chilli powder to a smooth paste ( with minimum water) in a mixer and keep aside.
Boil pineapple pieces with 1 ½ cups of water, green chilly and salt. When it is cooked ( approximately 10- 15 minutes ), add the ground coconut paste , mix it well and cook for some more time on low flame.
For the seasoning
In a frying pan , heat oil. Add mustard seeds. When they sputter, add jeera and curry leaves. Fry for 2 minutes and add the seasoning to the pineapple curry .
Tips: This makes an excellent side dish with rice. Some add curd to this preparation; but I decided not - as the curry already got a tangy taste from the pineapple.