Preheat your oven to 450 degrees Fahrenheit and adjust the oven racks to lower and middle positions.
In a shallow baking dish, place 1/4 cup flour.
In a small bowl, combine the buttermilk and egg. Whisk to combine. Stir in the remaining 1/4 cup flour, cayenne pepper, salt, black pepper, and hot sauce.
Using your food processor, pulse the potato chips and saltine crackers until you have a very fine, crumbly mixture. Place half of this mixture in a shallow baking dish and set the other half to the side. When you're halfway through coating the onion rings, add the rest of the crumbly mixture to the pan.
Slice onions into 1/2-inch thick rings. Discard any small pieces of onion.
Line a plate with wax paper. Begin coating the onion rings by first dipping each onion in flour. Then dip the onion ring in the batter, allowing any excess to drop off. Finally, coat the onion ring with the potato chip/saltine coating. Use your fingers to press the coating to the onion. Place each coated onion ring on the wax paper-lined plate.
When you're about halfway through coating the onion rings, prepare two rimmed baking pans by drizzling each with 3 tablespoons of oil.
Place the oil-coated pans in the oven for 8 minutes. While the oil is heating, finish coating the rest of the onion rings.
After 8 minutes, the oil will start to smoke. Remove the pans from the oven and *carefully* tilt each pan so that the oil coats the surface. Divide the onion rings among the two pans.
Bake the onion rings for about 8 minutes, then switch the pans around and bake for an additional 8 minutes or until they are crispy.
Place the baked onion rings on a paper towel-lined plate for a minute or two while you prepare the sauce.