Boil, cool, peel and grate the bananas. Heat the butter in a pan; add the carom seeds and sauté over medium heat for ten seconds. Add the mushrooms, carrots and broccoli and sauté till the moisture evaporates.
Add the fresh coriander, ginger, red chillies and salt. Stir, remove from heat and set aside to cool. Place the cooled mixture in a blender; add the prunes, black salt, pepper, cardamom, sandalwood and rose petal powders, potatoes, bananas and breadcrumbs and process till smooth.
Transfer the mixture to a bowl and divide into eight equal portions. Pat each portion onto a skewer to make four-inch long kababs. Preheat a tandoor. Cook in the tandoor for six to seven minutes.
Baste them with a little oil in between the cooking. Alternatively, shape each portion into a croquette, arrange on a greased tray and cook in a preheated oven at 180ºC/350ºF/Gas Mark 4 for six to seven minutes.
Arrange the kababs in a plate and serve them hot with Kachumber.