Step 1

For sauce, combine the first 9 ingredients in a small bowl. Cover and refrigerate at least 2 hours before serving.

Step 2

For onion, in a shallow bowl, combine flour and seasonings. In an electric skillet or deep fryer, heat oil to 375°. In another shallow bowl, whisk egg and milk. With a sharp knife, slice 1/2 in. off the top of the onion; peel onion. Cut into 16 wedges to within 1/2 in. of root end. Gently spread onion petals apart.

Step 3

Hold onion over dry ingredients. Spoon flour mixture over and around onion petals; shake off excess. Hold onion over egg mixture. Spoon over and around onion petals; allowing excess to drip off. Again, hold onion over dry ingredients. Spoon flour mixture over and around onion petals; shake off excess.

Step 4

Fry onion, cut-side down, for 3 minutes. Flip; fry until golden brown, about 3 minutes longer. Drain on paper towels; sprinkle with additional salt. Serve with sauce.