Dust the aubergine slices with the turmeric, salt, and 1/4 teaspoon red chile powder.
Heat the oil in a large, nonstick frying pan and fry the aubergine pieces until soft (you may have to do this in two batches). Set the fried aubergine aside.
In a bowl, beat 3/4 of the yogurt with the sugar, salt, and the remaining red chile powder. Pour the mixture into a small saucepan and heat gently, stirring often to prevent the sauce from splitting or breaking, for about 5 minutes.
Stir in the ground cumin and the fried aubergine slices. Heat gently and stir to combine.
Stir in the remaining yogurt, check and adjust the seasonings, as necessary and garnish with the fresh chopped cilantro.