Skin and thinly slice the chicken breasts, and set aside.
Grind the green chilies, garlic, ginger, onions and vinegar to a paste in a blender. In a large bowl, stir the paste into the shredded chicken and leave to marinate in the refrigerator for an hour or so.
Heat the oil in a wok and stir-fry the cumin and fennel seeds until aromatic. Add in the ma