Grind all curry powder ingredients in a spice grinder to a fine powder.
Season lamb shanks and sear in a hot casserole pan with oil until brown.
Blend chilli, garlic, and ginger into a paste with a splash of water.
Fry sliced onions in the same pan until softened and lightly colored.
Stir in 37 ml of curry powder, the aromatics paste, curry leaves, cardamom, and bay leaves.
Add lamb, tomatoes, stock, and tamarind then simmer covered for two hours.
Mix flour, salt, and water into a soft dough and rest for 10 minutes.
Divide dough into 12 balls and roll each very thin on a floured surface.
Fry chapatis in a hot oiled pan until golden and puffed.
Dust shallots in flour and fry in oil until crisp.
Reduce sauce until thick and serve over lamb shanks garnished with crispy shallots.