Start by peeling the large sweet onion. Slice it into 1/4-inch thick rings. Gently separate the rings and set them aside on a plate.
In a deep fryer or a large pot, heat the vegetable oil over medium-high heat. You want enough oil to fully submerge the onion rings, about 2-3 inches deep. Use a thermometer to ensure the oil reaches 350°F (175°C) for optimal frying.
In a mixing bowl, whisk together the all-purpose flour, baking powder, and salt. In another bowl, combine the buttermilk and the egg, whisking until well combined. Gradually add the wet ingredients into the dry ingredients, mixing until you have a smooth batter.
Dip each onion ring into the batter, ensuring it is fully coated. Allow any excess batter to drip off before moving to the next step.
After coating the onion rings in batter, roll them in panko breadcrumbs. Make sure each ring is fully coated for that extra crunch!
Carefully place a few onion rings into the hot oil, making sure not to overcrowd the pot. Fry them for about 2-3 minutes, or until they are golden brown and crispy. Use the slotted spoon to remove the onion rings from the oil, letting any excess oil drain off on paper towels.
Once all the onion rings are fried, serve them hot with your favorite dipping sauce, such as ranch, ketchup, or a spicy aioli. Enjoy the crispy, sweet goodness of your homemade onion rings!
