Wash karela and dry it completely. cut the head and tail (top and bottom part) and peel its skin. Cut the karela vertically into half and then make thin slices out of it. Chop all of the same ways.
Sprinkle some salt on chopped karela and mix well. Rest karela for 20-25 minutes, so it will release its bitter water.
Squeeze water from karela and keep it aside.
Also, cut the onion into two parts and cut it into slices.
Now coat karela strips with besan.
Heat oil in a pan and fry karela strips on medium flame till they become slightly crisp from the upper side. Keep it aside.
Now in the same oil, add onion and fry till it is slightly golden brown. Keep it aside.
Then in a mortal pestle, add peanuts, sesame seeds, and gathiya and crush it into a coarse powder.
Take out into mixing bowl, add turmeric powder, coriander powder, cumin powder, red chili powder, jaggery, garam masala, lemon juice, and coriander leaves. Mix well. Masala is ready.
Heat the oil in a pan on medium heat. Add mustard seeds, cumin seeds, hing, ginger paste, and green chili paste. Sauté for a minute.
Add karela and onion slices. Add salt and mix well.
Then add prepared masala on tindora and mix well.
cover and cook sabji for 5 minutes on low flame, so masala flavor absorb in it.
Garnish with coriander leaves and serve.