1. Preheat the oven to 150°C (300°F).
2. In a large bowl, combine the curry, turmeric, coconut milk, tamarind (or HP) sauce, lemongrass, sesame oil, peanut oil, and salt to make the marinade. Set aside.
3. Lay pork on a large sheet of aluminum foil and brush generously on all sides with (¾ of the marinade.
4. Refrigerate remaining marinade. Close foil around pork and seal tightly.
5. Transfer to a baking dish.
6. Place in oven and cook 6 to 8 hours.
7. Remove from oven and let sit for 30 minutes.
8. Open the foil packet, shred the pork, and add remaining marinade.

To make a sandwich:

1. Pour some peanut oil and a bit of whole cumin seed to a skillet over medium-high heat; fry a slice of naan on both sides. Set aside to cool.
2. Cut naan in half. Top with shredded pork. Add two tomato slices, some fresh cilantro, and mango slices.
3. Season with salt to taste and close sandwich.
4. Serve immediately or wrap tightly with plastic wrap and refrigerate for up to one day.

Chef's secret:

This recipe is easily prepared a day ahead of time. The sandwich can be eaten warm or reheated in microwave. For the lunchbox, place hot pulled pork filling in a thermos and make the sandwich on untoasted naan immediately before eating it.