Soak mustard seeds in vinegar for 30min
Mix sliced eggplant with turmeric powder, salt well
Deep fry in oil for 5min, stir occasionally
Remove the eggplants in a bowl, allow it to cool
Grind soaked mustard seed into fine paste
Fry onion and green chili a bit so that raw flavor goes away (optional)
Mix onion and green chili well with fried eggplant well along with mustard paste
Serve along with hot rice