Slice onions very thin.
Add salt to it and mix well.
Allow it to rest for 30 minutes.
Now after 30 minutes check onions.
Remove extra water settled. Keep it in a bowl and don't through it.
Now add in all ingredients and mix well.
Then add flour mixing everything. Don't add any extra water.
If you feel flour is more drier then just add that water we have removed from onions initially.
Give it a nice mix using hand or a wired whisk.