Mix together the cumin, coriander, cayenne and turmeric and toss with the chicken pieces.
Heat the oil in a large saucepan. Fry the chicken pieces in batches until deep golden, draining each batch to a plate. Add the onion to the pan and fry for 5 minutes until browned. Stir in the garlic and ginger and cook for a further 1 minute.
Return the chicken to the pan and add the measurement water. Bring to the boil, then reduce the heat and simmer very gently, covered, for 20 minutes until the chicken is cooked through. Add the lentils and cook for 5 minutes. Stir in the okra, coriander and a little salt and cook for a further 5 minutes until the lentils are tender but not completely pulpy.
Check the seasoning and serve in shallow bowls with lime wedges, chutney and poppadums.