Whisk together rajgira flour and yogurt to make a smooth mixture. Add four cups of water, green chillli-ginger paste, sugar and curry leaves. Cook on medium heat, stirring continuously, till kadhi thickens.
Add salt to taste. Heat ghee in a pan and add cumin seeds. When they begin to change colour, add it to the kadhi and mix well. Bring to a boil once and remove from heat. Serve hot garnished with chopped coriander leaves.