Heat 2 inches of oil in a large skillet or pot to 375°F.
Vegetable oil for frying
In a bowl, toss the onion rings with ¼ cup flour.
1¾ cups all-purpose flour, 2 medium yellow onions
In another bowl, combine 1½ cups flour, cornstarch, salt, baking powder, onion powder, garlic powder, paprika, and pepper.
¼ cup cornstarch, 1 tsp salt, ½ tsp baking powder, ½ tsp onion powder, ½ tsp garlic powder, ½ tsp paprika
Gradually pour in the beer while whisking to combine into a smooth batter.
1½ cups beer
Ensure the temperature of the oil is 375°F. Dip each onion slice in the batter until fully coated, letting the excess liquid drip off.
Working in batches, gently drop the onion slices into the oil. Fry for a couple minutes on each side until crispy and golden brown. Transfer to wire rack and immediately sprinkle with salt.
Serve with your favorite dipping sauce.