Slice the eggplants into slightly thicker discs. Sprinkle salt and turmeric powder on the slices of eggplant.
In a kadai, take 3 tablespoons of oil and heat it. Fry the eggplants on medium flame, till each side of the eggplant turns brown in color.
Keep the fried eggplants aside.
Take another kadai, and add 1 tablespoon of oil and heat it.
Temper the oil with nigella seeds. As the nigella seeds releases their aroma, add the mustard paste to the kadai.
Beat the yogurt well and add the yogurt to the kadai.
Add turmeric powder, red chili powder, salt, sugar and ground coconut to the kadai. (Remember, you had added salt while preparing the mustard paste).
Continue simmering till you achieve a desirable consistency. (The sauce/gravy should be semi dry. It should neither be completely dry or runny)
Lower the flame and gently drop the fried eggplants in the kadai.
Let it simmer for about 2-3 minutes and turn off the flame. Your begun basanti is ready to serve.