Cube the potatoes and set aside in water (so as not to blacken them).
Heat oil in a deep bottomed vessel, add the cumin seeds and curry leaves and let them splutter.
Add the potatoes and half cook them.
In a separate pan,heat oil and fry onion and add all the rest of the ingredients under stuffing and fry taking care not to burn any dry powders.
Let this cool down and grind into a smooth paste.
Remove the stems from brinjal and wash them thouroughly.
Slit them on the top in a cross and stuff them with the stuffing.
Add these brinjals to the half cooked potatoes and cook under lid until the brinjals are cooked.
Serve hot.