- Wash and soak channa dal for 2 to 3 hrs. Drain the water completely and keep aside. Grind together with other ingredients listed under "To grind" with 1 - 2 teaspoon of water into a coarse mixture (less water helps in crispy vadai texture. Avoid using too much water) 
- Transfer the mixture to the mixing bowl and add onions, curry leaves, coriander leaves and mix well 
- Preheat the oven to 400 degree Fahrenhait. Take the baking tray and brush the oil 
- Take small portions of the mixture, and flatten them using your palm (thinner vadai yields crispy vadai) 
- Place them in the greased tray and brush the top portion of each vadai with little oil to avoid drying out and of course for the crispy finish 
- Bake the vadai for 11 - 15 min, till they have browned the underside (adjust time according to your oven) . Carefully flip them and bake again for another 11 - 15 minutes. Remove and serve immediately. Serve with chutney/ ketchup. I generally love to finish them without any sides