Wash kerala thoroughly with water. If keralas are of longer variety, cut them into pieces of 3 inch size. Remove skin of all the pieces by scraping with a sharp knife.
Keep the skin aside. Slit the karelas length wise. Remove the seeds. Discard the seeds if very hard, otherwise mix them with the skin scrape.
Take 1 tsp salt and apply it thoroughly to all the pieces of karelas. Keep aside for about 1 hour.
Mix 1 tsp salt to karela skin and keep aside for 1 hour.
Heat a non sticking frying pan and add 2 tsp oil. When the oil becomes hot, add cummin seeds and hing. When the seeds becomes dark, add onion, green chili, ginger and garlic. Cook for 2-3 minutes and add all the spices and besan. Stir well and cook until the mixture turns light brown, about 5-7 minutes. Mix half the coriander leaves.
Take the karela skin in a sieve and wash thoroughly with water. Add it to the washed skin scrape above mixture and stir.
Wash the karelas with water. Fill the above mixture in each karela.
Heat a non sticking frying pan and spray oil. Place all the karelas in the pan, cover with a lid and reduce the stove to low. Let them cook for 5-7 minutes. Change the side of karelas and again cover with the lid. Kook for 5-7 minutes. Sprinkle coriander leaves.
Serve with roti, chapatti, bread, etc. or use for burgers.