Put the chicken in a shallow glass bowl, pour over all the ingredients except the chickpea flour, oil and butter, mix well to coat all the pieces and marinate in the fridge for 2 hours. The add the chickpea flour and oil, mix thoroughly, cover tightly and refrigerate overnight.
Preheat the oven on max temperature, then turn on the grill at 230°C and place a tray underneath to catch the drippings and thread the chicken onto metal or wooden skewers.
Grill the tikkas, a few skewers at a time first for 4 minutes, then baste the tikkas with melted butter or ghee, turn and grill for a further 4 minute-5 minutes till done. The tikkas should have a light char and should not be allowed to dry out and burn.
Remove the skewers and rest vertically for to allow any moisture to drip away. Gently remove the tikkas and serve with fresh mint chutney.