Soak tamarind pulp in hot water for 30 minutes until softened. Drain and remove any hard pieces. Combine the softened tamarind with the lime juice, sliced chilli pepper, pressed garlic, brown sugar, Worcestershire sauce, salt, and pepper to make the braising sauce.
Trim the fat from the pork fillet and cut into 1 cm cubes. Finely dice the onion.
Heat the clarified butter in a saucepan over medium-high heat. Sear the pork cubes until browned. Add the diced onion and fry together for 2 minutes. Pour in the braising sauce, canned tomatoes, sliced spring onions, and beef stock.
Bring the mixture to a boil over high heat. Reduce heat to low and simmer for 1 to 2 hours, stirring occasionally. Add more beef stock or water if needed. The pork is done when it reaches an internal temperature of 63°C (145°F).
Sprinkle chopped coriander over the braised pork when serving. Serve with naan bread and yogurt-mint dip.