Grind curry powder ingredients into a fine powder using a spice grinder or pestle and mortar.
Preheat the oven to 170°C.
Season lamb with salt, pepper, and 2 tbsp of curry paste, drizzle with oil, and roast for 2 to 4 hours.
Blend chilli, garlic, and ginger into a paste using a food processor.
Fry onions in a pan over high heat for 2-3 minutes until softened and colored.
Add 2.5 tbsp curry powder, the aromatics paste, curry leaves, cardamom, and bay leaves to the pan.
Add tomatoes, 200ml beef stock, and tamarind juice, then simmer covered for 30-40 minutes.
Shred the rested lamb meat into the sauce and stir in fresh coriander.
Mix flour, salt, and 200ml water to form a soft dough, then rest for 10 minutes.
Divide dough into 12 balls, roll thinly, and fry in oil for 1-2 minutes per side.
Boil rice in 350ml salted water, then steam for 10 minutes before stirring in coriander.
Serve the curry in bowls with the rice and chapatis on the side.