Peel the bitter gourd, slit each bitter gourd lengthwise and scoop out the insides carefully creating a hollow in the centre.
Apply a little salt to the inside and outside of the bitter gourd and keep aside for 10 minutes.
Wash the bitter gourd and pat it dry using a kitchen towel. Keep aside.
Heat the mustard oil in a broad non-stick pan, add the cumin seeds .
When the seeds crackle, add the onion paste and sauté on a medium flame for 3 minutes.
Add the ginger, green chilli paste, turmeric powder, dried mango powder, garam masala, salt and coriander, mix well and cook on a medium flame for 2 minutes, while stirring occasionally.
Fill a portion of the prepared mixture into each slit bitter gourd and tie with a thread all over.
Heat the oil in a deep non-stick pan, add the tied bitter gourd two at a time and cook on a medium flame till they turn golden brown in colour from all the sides. Drain on an absorbent paper.
cut or remove the thread nd serve..