Slice eggplant lenghthwise about 3/4 inch thick. Sprinkle slices with salt and set aside.
Finely mince garlic and ginger, sprinkle with little salt, mince some more until nearly mashed.
Slice onions thinly.
Seed and finely chop red and green chili peppers.
In a deep skillet, heat ghee and fry sliced onions until soft and lightly browned.
Meanwhile, pat eggplant slices dry and cube them.
Add red and green chili peppers, minced garlic and ginger, curry leaves, mustard seeds, cumin seeds and ground coriander to the onions, fry, stirring, until fragrant, then add tomato paste and tamarind puree, stir and add eggplant cubes.
Fry one more minute, then add coconut milk, bring to a gentle boil, cover and let simmer for about 20 minutes or until eggplant is soft.