Cut the chicken into small chunks, about 2cm square.
Heat the butter in a karahi or wok to quite a high heat. Add the cumin seeds and stir-fry for about 30 seconds. Add the ground cumin and continue to stir-fry for a further 30 seconds, then add 3-4tbsp stock or water and stir-fry for 2-3 minutes more.
Add the chicken and stir-fry briskly for about 2 minutes, then lower the heat a little and, over the next 5 minutes, add the remaining stock or water, stirring as necessary.