First of all peel the skin off Bitter Melon and keep aside.
Cut Karela in the shape of thin rings.
Make a paste of salt, turmeric, ginger and garlic. Add karela rings to this paste and mix nicely. Keep it aside for an hour.
Now heat mustard oil in a pan and let it smoke out. Whn oil is warm, add onion and fry till it is golden brown.
Add cumin powder, red Chilli powder, turmeric powder and salt and stir it.
Now add karela pieces and cover the pan, keep the flames low.
Let it it cook for 5 minutes on low / medium flames. Add mango paste now and cook further in a covered pan for 10 - 15 minutes on low / medium flames.
Check if Karela is cooked. Cook until karela is soft.
Karela Sabzi is ready.
Serve it with chapati.