Peel the onions and cut off the stem ends. Slice crosswise into 1/2-inch to 3/4-inch thick rings. Gently separate into individual rings and set aside.

Soak to reduce pungency and crispness

Place the separated rings into a bowl. Mix cold water, ice cubes and 1 tsp salt and pour over the rings so they are submerged. Let soak 30 minutes refrigerated or at least 15 minutes at room temperature. Drain and pat very dry with paper towels — removing surface moisture is crucial for batter adhesion and oil safety.

Breading and Batter

Prepare dry mix

In a large bowl whisk together 1.5 cups all-purpose flour, 1/4 cup cornstarch, 1 tsp baking powder, 1 tsp kosher salt, 1/2 tsp black pepper, 1/2 tsp smoked paprika and 1/4 tsp garlic powder until evenly combined.

Make beer batter

Whisk the egg lightly in a separate bowl. Add the 1 cup cold beer (or cold sparkling water) and 1/4 cup cold buttermilk if using. Slowly pour the wet mix into the dry mix, whisking until just combined. Batter should be thick enough to coat the back of a spoon but still pourable. If too thick, add a tablespoon of cold beer or water at a time until desired consistency is reached. Keep batter cold by placing bowl over another bowl filled with ice if you plan to wait.

Dredge

Prepare dredge mixture

In a shallow bowl or tray combine 3/4 cup flour, 1/4 cup cornmeal (if using), 1/2 tsp salt and 1/4 tsp black pepper. Mix well. This dry dredge helps the batter cling and adds extra crunch.

Dredge onions: Work in small batches. Toss a few dried onion rings in the dredge to coat lightly, shake off excess, then dip into the batter allowing excess to drip back into the bowl. For an extra-crispy double-coat, after battering you can briefly return rings to the dredge and tap off excess. Transfer battered rings to a wire rack while you heat oil.

Finishing & Frying

Heat oil

Pour 4–6 cups oil into a heavy-bottomed pot or deep fryer, leaving at least 3 inches headspace. Heat oil to 365°F (185°C). If you don't have a thermometer, heat until a 1-inch cube of bread browns in about 60 seconds (approximate). Maintain 350–365°F while frying — adjusting heat between batches to avoid oil temperature drop.

Fry rings

Working in small batches (4–6 rings depending on pot size), carefully lower battered rings into hot oil. Fry until golden brown and crisp, about 2.5–3.5 minutes per batch, turning if necessary for even color. Use a slotted spoon or spider to remove rings and let drain on a wire rack set over a baking sheet (not paper towel — rack keeps crispness).

Finish and season

While still warm, sprinkle rings lightly with fine salt or seasoned salt to taste and optional chopped parsley. Serve immediately for best texture.

Sauce (Optional - Cajun Aioli)

Whisk together 1/2 cup mayonnaise, 1/4 tsp smoked paprika, 1 tsp hot sauce, 1 tsp lemon juice, 1/4 tsp garlic powder and 1/8 tsp salt until smooth. Refrigerate until serving. Serve alongside hot onion rings for dipping.