Soak spilt Bengal gram in water for minimum an hour. Drain the liquid.
Now grind the soaked Bengal gram, salt, fennel powder to a coarse dough by not added any water.
Now add onion, ginger, curry leaves, green chili to the vadai dough and mix well.
Heat oil in a pan for frying. Now make balls size of small lemon with the dough. flatten the balls and deep fry them to golden brown and serve. NOTE: cook them in batches for good result and also make sure they are cooked.
Dip in water when you make balls and flattening so the dough does not stick to your hand. You can also use banana leaf to flatten it.