Method
In a blender, purée the lime juice, garlic, ginger, and chillies.
Add the yoghurt, spices and colour and blend until smooth. Mix with the chicken pieces and leave over night, if possible. If not, your chicken will need at least 4 hours in the marinade. Separate the green and white parts of the leeks. Blanch the whites of the leeks in boiling water. Wrap the prunes in the green parts of the leeks. Thread the chicken, wrapped prunes and blanched leeks onto your prepared skewers.
NB: if you are using wooden skewers make sure you soak them so they don't burn.
Heat the grill to a high heat and lightly oil the grates. Place the skewers on the grill.
Cover the grill and cook, turning occasionally until grill marks are visible and the chicken is cooked. If you do not have a grill, then you can use a very hot oven.
Serve with tamarind sauce.