Make Moong dal Dumplings: Soak moong dal for 3-4 hours and grind it to a smooth paste using little or no water. Add all the other ingredients and keep aside.
At this point you have 2 options: Drop the batter directly in the kadhi or par cook the dumplings in the microwave and then drop them into kadhi. I microwaved my dumplings.
Make Kadhi: In a nonstick saucepan, combine yogurt, besan and 1cup of water and whisk to make sure that there are no lumps. Add grated ginger, minced green chilies, sugar and salt and mix well. Bring this mixture to a boil, stirring occasionally, on medium flame. Keep aside.
Heat 2tsp oil in a small saucepan, add mustard seeds and cumin seeds and once the seeds start to splutter, add dry red chili and curry leaves. Add the tempering to the kadhi, mix well and bring it back to a boil.
Add Moong dal dumplings (either microwaved or the batter directly) to the boiling kadhi and let cook for 5-8 minutes. Once the dumplings are completely cooked, they tend to float up to the surface.
Garnish with chopped cilantro and serve with rotlas or rice.