Take part of the soaked rice mixture into a grinder, then add just enough water to grind. Make sure that your grinder doesn’t overheat. If it gets too hot then it may ruin the batter. You can try these tips to avoid overheating the grinder, grind it in a short burst, reduce the quantity, keep it in the fridge before grinding, stop the grinder often, etc.
Pour the batter into a metal bowl. Grind the remaining rice mixture. Don’t add salt at this time
Mix with your hand. This will add air to the batter and helps with fermentation. It is good to mix with hand for 2-3 minutes
Cover with a lid and towel and ferment it for 12 hours. You will know when the batter is ready, it will increase in volume, you may also see tiny bubbles on them.
After fermentation, remove the cover. Mix it lightly, you don’t want to remove all the aeration in the batter. Add enough salt and maybe little water if needed. The batter should not be too thick or too thin. It should be in flowing consistency