Soak dal for 3 hours .Drain the water completely. Grind dal with all other ingredients , add besan flour and salt, mix it well.
Make small balls with dal mix. Wet your hands and flatten each balls with your palms.Heat oil in a deep pan and fry the vadas on medium flame till it becomes crispy and brown colour.
Moong dal vada is ready. Serve hot with tea or coffee.