Preheat oven to 350F. Line two baking sheets with parchment paper and spray with cooking spray.
In a large bowl, mix together flour, potato starch, cornstarch, cayenne pepper, garlic powder, salt and pepper and whisk until combined. Slowly drizzle in sparkling water while whisking until you reach a thick but pourable consistency (Somewhere around 1 1/4 cup worked for me). If the batter is too thick it will be hard to get the chips to stick.
Place the potato chips in a separate bowl. You will not want to put all of the chips in there at once since the batter will sometimes get the chips too wet that they will not stick. So it is best to add chips to this bowl a little at each time.
Now take an onion ring, cover it in the batter and then place it in the bowl with the potato chips. With a clean hand, pour some chips from the bowl over the onion to help cover it. You do not want sticky or wet hands at all because it will make the potato chips too wet to use. Place the ring on the baking sheet and repeat with remaining onions.
Bake at 350F for 20 minutes, flipping half way through. Eat immediately.
Serves 3-4 people as a snack