To break it down: you first add a spice mixture to hot mustard oil (tempering). Then you add chopped onion. Afterwards chopped tomato. In this stage you add spice mixtures. Then you add potato wedged and fry for 10 minutes. Add eggplant and then simmer for 10 minutes. Add a little water (150 ml or so) and simmer until the potatoes are done. In my case another 20 minutes.