Place onions in a medium nonreactive heatproof bowl.
In a small saucepan, combine hot sauce and all remaining ingredients. Cook over medium-high heat until sugar is dissolved, 1 to 2 minutes. Pour mixture over onions. Cover with a piece of plastic wrap, pressing wrap directly onto surface of pickling liquid to keep onion submerged. Refrigerate overnight. Drain and pat dry before frying.
Notes
*We used Crystal Hot Sauce.
Recipe by Taste of the South at https://tasteofthesouthmagazine.com/classic-green-bean-casserole/