Mix all dry ingredients in one bowl. Whisk all wet ingredients in another bowl.
Add the wet ingredients into the bowl with the dry ingredients. Mix until fully incorporated. If the batter is not wet enough to dredge the onion rings you can add more beer.
Soak all the onion rings in the batter. Remove the onion rings and shake off excess batter.
Carefully lower rings in the oil. Don't overcrowd the pan.
Remove when they turn golden brown. Place on wire rack over paper towel lined baking sheet. Season with salt.