Evenly season the chicken with salt and turmeric; set aside for 15 minutes.
Heat the oil in a large frypan over medium heat. Cook the onions in the hot oil until browned; about 5 minutes. Add the chicken and cook until browned; about 5 minutes more. Stir the capsicums and chillies into the chicken; continue cooking another 5 minutes.
Grind the cumin seed, coriander seed, black peppercorns, cinnamon, cloves, cardamom pod and fennel seed into a coarse powder; sprinkle over the mixture in the frypan.
Add the water, coconut milk powder and salt. Cook until the chicken is tender; about 30 minutes. If the curry is too wet cook on high until the moisture evaporates. Garnish with coriander and serve hot.