Firstly, clean vazhaipoo and chop as finely.
Wash & soak chana dal, urad dal,rice (if adding) together for 2- 3 hours.
In blender, grind chilli, jeera/fennel first and then add the dal, drained from water.
Grind coarsely. you can do it in two batches.
Then add the chopped vazhaipoo and grind to your desired consistency.
Transfer to a mixing bowl and add the chopped onion, salt, asafoetida, coriander, curry leaves. Mix well.
Heat oil in kadai. Grease your hands with water and make medium sized patties/ vadai in your palm.
Drop the vadai in oil and cook in medium flame. You can fry 4-5 at a time.
Fry both sides until golden and crisp or until the inside gets cooked well.
Drain to paper towel and enjoy hot. Its very flavourful even when its cooled down.