I used a cast iron dutch oven to fry these in. It's a really heavy pot and I felt like I didn't have to worry about splatter quite as much.
3 sweet onions, peeled and sliced
1 cup buttermilk
2 cups flour
1 tablespoon Old Bay
Oil for frying (vegetable, peanut, etc)
In a wide, shallow dish mix the flour with the Old Bay seasoning. Pour the milk in a second dish.
In a deep pot or dutch oven add the oil and heat on a medium high until around 360 degrees.
Take each onion ring and toss in the flour mixture. Then dip in the milk and then toss back in the flour. Carefully drop the rings into the oil and fry until golden brown. I only fried 2-3 at a time so the oil temperature would stay hot.
Drain the rings on paper towels or racks and sprinkle with salt while still hot.
If you like spicy onion rings feel free to add some hot sauce to the milk.