Mix the besan, cayenne, turmeric, mango powder and salt and toss the eggplants in it. Add some water if needed to help the besan stick to the eggplants.
Place the eggplant pieces under a broiler for about 10-15 minutes or until the eggplants are tender. Toss every few minutes with a ladle to ensure all sides cook evenly. Keep an eye on the eggplants when they are under the broiler because they can burn fast. Once they are cooked, set aside.
Heat the oil and add the mustard seeds. When they crackle, add the onions, ginger, garlic, and curry leaves.
Saute, stirring frequently, until brown spots appear on the onions. If the ginger and garlic stick to the bottom of the pan, add a little water.
Add the cumin and coriander powders, cayenne, and the garam masala. Saute for a minute, then add the methi leaves and salt.
Saute the methi on medium-low heat until it starts to tenderize.
Add the tomatoes or tomato paste and ½ cup of water. Mix thoroughly, cover, and let the mixture cook for about 8 minutes or until the methi is cooked and tender.
Add the eggplants and stir them in. Cook for another two minutes, check for salt, then turn off the heat.
Garnish, if you like, with some fresh coriander. Serve hot.