Slice the pineapple in half lengthwise. Use a knife and spoon to gently scoop out the fruit, leaving about 1 cm around the edges. Chop the flesh into small pieces and set aside. Keep the pineapple shells—you’ll serve the curry in them later.
Toss the shrimp with a little salt and half the turmeric (about ¼ tsp). Let it sit while you start the curry.
Heat coconut oil in a large pan. Add the mustard seeds and let them pop. Then toss in the bay leaf, onion, green chilies, garlic, and ginger. Cook on medium heat until everything softens and smells amazing.
Stir in the tomato and tomato paste. Let it cook down for 2–3 minutes. Then add cumin, coriander, chili powder (if using), and the rest of the turmeric. Cook for another minute or two until it forms a nice, thick base.
Add pineapple & shrimp:
Add the chopped pineapple and shrimp to the pan. Stir well to coat everything in the spice mix.
Pour in 100 ml water and, if you’re using it, 100 ml coconut milk. Add salt, bring it to a simmer, and let it cook for about 5–7 minutes—just until the shrimp are cooked through and the sauce thickens a bit.
Squeeze in some lime juice (or stir in a little tamarind paste) to balance the sweetness. Taste and adjust salt or chili if needed.
Spoon the curry into the hollowed-out pineapple halves. Sprinkle with fresh cilantro and serve hot with steamed basmati rice.