Peel and chop pineapples into bite-sized pieces.
Transfer to a saucepan with water enough to cover it and bring to a boil.
Once it comes to a boil, reduce heat and simmer covered until slightly cooked.
Add jaggery to taste as well as a pinch of salt (to balance the flavors), mix well and cook for a few more minutes until the jaggery has dissolved and the pineapple mixture is slightly thick.

Remove from heat and let cool completely. At this stage, once it is cooled, you can refrigerate until you are ready to add the mango and coconut masala and serve.

To make the coconut masala:
In a blender jar, make a smooth paste of grated (fresh or frozen) coconut, red chillies (do not add more than 2) and mustard seeds.
Just before serving, stir in chopped mango pieces along with raisins (or grapes) and coconut-mustard masala into the cooked and cooled pineapple; mix well. Adjust the taste and consistency of the gravy to your preference. It is generally serve slightly thick.

Cooked pineapple will have some gravy so adjust accordingly.
Serve chilled or at room temperature; store leftovers in the refrigerator.

Another popular version is adding the pineapple uncooked. If you are short on time, you can make the saasam with uncooked pineapple too.

Do not add more red chillies as the curry may become too spicy. It is amazing how just only one or two red chillies can spice up this mixture.

When mangoes are not in season, you can make this dish with chopped apples and grapes or use frozen or canned mango chunks.

For more flavor, you can season the dish with mustard and curry leaves in coconut oil; totally optional.