1) Cut the chicken into small cubes and set aside.
2) In a large bowl, combine the yoghurt, mustard, curry powder, cumin and cayenne pepper.
3) Mix in the chicken and sultanas. Season with salt, pepper and more cayenne, if desired.
4) To keep the cashews crunchy, mix them in just before serving.
Serve as an open sandwich or on crispbread or on a bed of lettuce as a salad.