Step 1

Whisk together flour, cornstarch, dry potato flakes, and cayenne pepper in a large bowl. Whisk in club soda to make a smooth batter.

Step 2

Place panko bread crumbs in a shallow bowl.

Step 3

Heat oil in a deep fryer or large saucepan to 350 degrees F (175 degrees C).

Step 4

Place a few onion rings at a time into the bowl of batter and turn to coat all sides with batter.

Step 5

Remove onion rings from batter and place into pan of panko bread crumbs; turn to coat completely with crumbs.

Step 6

Cook a few rings at a time in the hot oil until golden brown, about 2 to 3 minutes.

Step 7

Transfer to a cooling rack set over paper towels to drain. Season with salt to taste and serve.