Deep fry the eggplant slices a few at a time in hot oil until lightly browned. Drain on kitchen paper towels.
Heat extra oil in a saucepan, add onions and mustard seeds and cook, stirring, until onion is soft and seeds start popping, about 4 minutes. Stir in sesame seeds and cook another minute.
Stir in sultanas, nuts, chilli powder, turmeric, flour and sugar. Cook over medium heat 2 more minutes.
Stir in lemon juice and yoghurt. Bring to a simmer and simmer on reduced heat 3 minutes. Serve with the eggplants.