Prepare a tandoor for moderate heat, or alternatively preheat the grill (broiler) to medium.
Put all the ingredients for the aromatic potli in a piece of muslin (cheesecloth) and tie together with kitchen string (twine) to make a pouch.
Bring a pan of water to the boil.
Add the potli together with the colocasia and boil until colocasia is soft.
Drain, discarding the potli, then peel off the skin, return to the pan and mash until smooth.
Put all the ingredients for the masala for sprinkling in a bowl and mix together.
Put the mashed colocasia, paneer, khoya, mint, ginger, chillies, ground pomegranate seeds, almonds, plums, ground fenugreek and salt to taste.
Add three-quarters of the masala, mix well, then mash with a potato masher.
Divide the mixture into 12 equal portions and roll into balls.
Using damp hands, spread the balls along the length of 4 metal skewers, flattening the mixture into a sausage shape until the kebabs are 10cm / 4 inches long.
You could make 2 kebabs along 1 skewer if the skewers are long.
Roast in a moderately hot tandoor or under the hot grill for 3-4 minutes, or until golden.
Remove gently from the skewers, arrange on a platter and sprinkle over the remaining masala