Begin by slicing the onion into 1/2-inch thick rings. Separate the rings and set them aside in a bowl.
In a separate bowl, combine the milk and white vinegar. Let it sit for about 5 minutes to thicken slightly.
In another bowl, mix the sour cream, all-purpose flour, salt, black pepper, and garlic powder. Pour in the buttermilk mixture and stir until just combined. The batter should be thick but pourable.
In a large pot or deep fryer, heat oil over medium-high heat until it reaches 350°F (175°C). Use a thermometer for accuracy; this temperature is key for achieving crispy onion rings.
Dip each onion ring into the batter, ensuring it’s fully coated, then carefully drop it into the hot oil. Fry in batches to avoid overcrowding, which can lower the oil temperature. Fry for about 3-4 minutes or until golden brown.
Using a slotted spoon, remove the onion rings from the oil and place them on a cooling rack lined with paper towels. This allows excess oil to drain off while keeping the rings crispy.
For a simple dipping sauce, mix together equal parts of sour cream and your favorite hot sauce or a dash of vinegar for tanginess. Adjust the flavors to your liking!
Serve the crispy onion rings with the dipping sauce on the side and watch them disappear in no time. Enjoy the crunchy goodness with family and friends!