First soak the urad dal overnight or for 5 to 6 hours. Now drain the excess water and add it to the grinding jar. Add 3 to 4 tbsp of water while grinding. Along with it add the ginger cubes too. I've added salt too while grinding. Now grind them into a fine paste.

Remove this mixture in a vessel. Now start whisking the mixture until it becomes light and fluffy. Whisk the batter for about 7 minutes continuously. Note : If you want to check whether it's done or not, take a small bowl filled with water and drop a drop of batter in it. If the batter floats on the water then your batter is perfectly done. But if it sinks down then you need to whisk more until it floats on water.

Now once it's done, add chopped onion, baking soda, chopped green chillies, curry leaves, chopped coriander, ajwain, jeera and if required salt too. Now give everything a good mix.

Now heat some oil in a pan for deep-frying. Once the oil gets hot, drop little batter in the oil. (about a tbsp). Put them carefully while dropping the batter so that oil doesn't spills out and burns your hands. Keep the flame medium and fry the gulgulis until they become golden from both the sides as shown below in the image.

Repeat the same with the rest of the batter. One it's done, remove them on a tissue so that all the excess oil gets soaked up in the tissue. Your gulgulis are now ready to serve. Serve them with some tomato ketchup.