Cut potatoes in one inch cubes and eggplant in long slices and put it in salt water. Potatoes and eggplant won't turn black.
Heat oil in a pan add mustard seeds when they start to splutter add cumin seeds green chilli onions and let them soften
The onions are cooked and they should look like this
Now add potato and eggplant and mix it well cover with a lid and let it cook on a low flame for five minutes
Mix this slowly without breaking the vegetables
Add tomatoes, chilli powder, turmeric, coriander powder and mix . Now cover and cook for another 3-5 minutes till these are done
Serve it with a parantha or any other Indian bread. Enjoy!!!