Whisk yogurt with salt and two and half cups of water to make very thin buttermilk. Set aside.
Heat olive oil in a kadai (wok), add split black gram and mustard seeds and fry for a minute.
When the mustard seeds begin to splutter, add curry leaves, onion, tomatoes, carrots and green chillies and saute for a minute.
Add rawa and continue to saute on medium heat for four to five minutes till it is lightly coloured and fragrant.
Add buttermilk, bring to a boil, reduce heat and continue to cook uncovered, stirring continuously, till all the liquid is absorbed.
Adjust seasoning, cover and cook further for two minutes on very low heat. Add olives and coriander leaves. Stir and cook for a minute. Serve hot.