Pour the vegetable into a large pot and heat over medium heat until the oil reaches 365 degrees f.
6 cups vegetable oil
While the oil is heating whisk together flour, salt, pepper, garlic powder, paprika and baking powder.
5 ounces all-purpose flour, 1 teaspoon salt, ½ teaspoon black pepper, ¾ teaspoon garlic powder, ½ teaspoon paprika, ½ teaspoon baking powder
Dip the onion rings into the flour mixture and shake off the excess flour.
2 large yellow onions
Place the coated onions on a baking sheet, and set aside the remaining flour mixture.
In a measuring cup whisk together the buttermilk and egg until well combined. Add the buttermilk mixture to the reserved flour and whisk until blended.
1 cup buttermilk, 1 large egg
Add the panko breadcrumbs to another shallow dish.
2 ½ cups Panko bread crumbs
Dip the onion rings into batter and then shake off excess batter. Then dip in the panko. Shake off the excess breading.
Place them in the preheated oil and deep fry them until golden brown. Flip them halfway through frying.
Drain on a paper towel lined plate or baking sheet.
Repeat the process until all the onion rings are cooked. It's best to work in batches of no more than 10.
Serve warm with ketchup or fry sauce.