Wash and dry the naarthangai.
Cut it into tiny slices.
In a pressure cooker, add the cut naarthangai, salt and water.
Pressure cook for 10-15 minutes.
Remove the lid of the cooker, add the red chilly powder and mix well.
Grind together mustard seeds and fenugreek seeds in a small mixer jar.
Add it to the pickle and bring it to a boil.
Remove from flame.
Heat oil in a pan and add mustard seeds and curry leaves.
When the crackle add it to the pickle.
Allow it to cool completely before transferring to a pickle jar.