In a bowl, combine the fine besan, coarse besan, turmeric powder, hing powder, crushed coriander seeds, crushed ajwain (carom), crushed cumin seeds, chopped onion, ginger-garlic-green chilli paste, red chilli powder, and salt.
Add chopped coriander leaves and mix all the dry ingredients well without adding water first.
Gradually add water, a little at a time, and mix to form a smooth batter. The total amount of water used was about 1 ½ bowls.
Whisk the batter well for about 2 minutes.
Optional: You can add a teaspoon of hot oil to the batter at this stage.
Add a pinch of baking soda to the batter and mix it in.
Heat oil in a kadai (wok) over medium heat.
Drop small portions of the batter into the hot oil and fry them until they are lightly golden. Do not overcrowd the kadai.
Remove the partially fried bhajis (pakodas) from the oil after about one minute of flipping them.
Place the partially fried bhajis (pakodas) on a plate and press them down to flatten them.
Once all the bhajis (pakodas) are flattened, put them back into the hot oil and fry them again until they become golden brown and crispy. You can increase the heat to medium-high for this second frying.
Fry the slit green chillies in the hot oil and remove them.
Serve the crispy, flattened bhajis (pakodas) hot, garnished with the fried green chillies.