Barbecue legends, such as Leonard Heuberger of Memphis and Sonny Bryan of Dallas, among others, liked crispy buttermilk-soaked onion rings with their ribs and brisket. Sweet onions are particularly good in this recipe.
Cut the onions into ¼-inch-thick slices. In a nonreactive dish, soak the onions in the buttermilk for 30 to 60 minutes.
In a brown paper sack, combine the flour, cornmeal, salt, onion powder, chili powder, and, if needed, sugar. Drain the onions lightly and dredge them in the seasoned flour.
Pour at least 4 inches of oil into a heavy saucepan. Heat th