Boil, peel and mash raw bananas, colocassia and potatoes separately. Finely chop ginger, green chillies, coriander leaves and mint leaves. In big bowl mix bananas, colocassia, potatoes, green chillies, coriander leaves, mint leaves, ginger, salt, coriander-cumin powder, refined flour and dried mango powder well. Grease your palms, take a portion of the mixture and pat it around a seekh or wooden skewer. Make more seekhs in the same way.
Heat a little oil in a non stick pan, place the skewers on it and cook, rotating the skewers, till they are cooked evenly and golden all around. Serve hot.