Whisk together the buttermilk, hot sauce and 2 teaspoons of the Essence in a large bowl. Add onion rings and press to coat evenly with buttermilk mixture.
Cover and marinate in the refrigerator for 1 hour.

Heat enough oil to come halfway up the sides of a medium pot to 360˚F.

Combine the flour with 2 tablespoons of the Essence in a shallow bowl. Dredge the onions in the seasoned flour, tossing to coat each ring evenly, and shake off any excess flour. Carefully add onions to the hot oil, in batches, and fry until golden brown, turning with a spider or long handled slotted spoon to cook evenly and prevent sticking, about 3 minutes per batch.
Drain on paper towels and season with the remaining teaspoon of Essence.
Serve hot.