1.Make spice blend by combining spices in a small bowl.
2.Heat 2 tbsp of the oil in large saucepan. In batches, cook chicken until browned all over. Remove from pan.
3.Heat remaining oil in same pan. Stir onion over heat until soft. Add garlic, ginger and curry leaves; continue stirring until fragrant. Add spice blend and stir about 2 minutes or until fragrant.
4.Return chicken to pan with undrained tomatoes, stock and lemongrass; bring to the boil. Reduce heat and simmer with lid on, stirring occasionally, for 20 minutes. Remove saucepan lid and simmer about 10 minutes or until sauce thickens slightly. Discard lemongrass.
5.Add coconut milk and stir until heated through. Serve curry sprinkled with coriander.