Slice onions very thin, separate, and place in a gallon size baggie.
Pour buttermilk into baggie with onions, close, shake to coat onions, place in the fridge and let sit in baggie for 40-45 minutes.
In another gallon size baggie, add flour, garlic salt, Slap Ya Mama® seasoning, paprika and black pepper. Seal, shake to mix, and set aside.
While onions are soaking, heat oil to 375° in a cast iron skillet or a large pot.
Remove ½ of the thinly sliced onions from buttermilk with tongs, shake off excess buttermilk. Add to the flour mixture. Seal baggie and shake to coat onions.
Use tongs to remove the onions from the flour mixture and gently place onions into the hot oil.
Cook until golden brown and desired crispiness is obtained, stirring occasionally.
Carefully remove from oil and place on a plate lined with paper towels.
Repeat until all onion strings are cooked.