For eggplants in yogurt sauce, wash eggplants and pat dry with kitchen paper. Then place in a baking dish and bake for 45 minutes in a preheated oven at 160 degrees.
Take out and let cool. Cut each eggplant in half lengthwise with a sharp knife and scoop out the flesh with a spoon.
Discard the skins and set the flesh aside. Heat the oil in a large pot. Add the onion rings and cumin and stir-fry for 1-2 minutes.
Add the chili powder, salt, yogurt and mint sauce to the pot and stir well. Add the eggplant flesh to the onion-yogurt mixture and stir-fry for 5-7 minutes, until all the liquid is absorbed and the mixture has thickened.
Transfer the eggplant in yogurt sauce to a serving bowl and garnish with the chopped mint leaves.