Prepare the Dal: Take the soaked moong dal and drain all the water completely. You don't want any extra water.
Grind the Dal: Add the drained dal to a mixer grinder. Grind it coarsely using the pulse button ("stop-start" mode). It's very important not to make a smooth paste. The batter should be "dardari" (coarse), with some whole dal visible.
Mix the Batter: Transfer this coarse dal paste to a large mixing bowl.
Add Aromatics: Add the chopped onions (if using), crushed green chillies, lightly crushed cumin seeds, carom seeds, coarse coriander seeds, asafoetida, turmeric powder, and curry leaves.
Add Final Touches: Add the chopped coriander leaves, salt to taste, and the rice flour. The rice flour is key to making the Moong Dal Bhaji extra crispy.
Combine Well: Mix everything together with your hands or a spoon until well combined. Your batter is now ready.
Heat the Oil: Heat oil in a kadai (wok) for deep frying. The oil should be very hot ("kadak garam").
Fry the Bhajis: Once the oil is hot, reduce the flame to medium. Carefully drop small portions of the batter into the hot oil. Don't overcrowd the pan.
Be Patient: Let the bhajis fry undisturbed for about a minute. After a minute, gently stir them.
Fry till Golden: Continue frying on medium heat, stirring occasionally, until the bhajis are a beautiful golden-brown colour and are perfectly crispy on the outside.
Drain and Serve: Remove the crispy Moong Dal Bhajis with a slotted spoon, draining the excess oil. Serve them hot!