Peel the onions and slice into 1/2-inch thick rings. Gently separate into individual rings and set aside. You should have about 10 large rings; choose the largest rings for serving if needed.

Make Dry Mixes

In a medium bowl combine 1 cup all-purpose flour, 1/4 cup cornstarch, 1 tsp baking powder, 1 tsp salt, 1/2 tsp black pepper, 1/2 tsp paprika and 1/2 tsp garlic powder. In a separate shallow bowl place 1/2 cup flour (for dredging). In another shallow bowl place 1 cup panko breadcrumbs and sprinkle 1/4 tsp salt into the panko; mix to incorporate.

Make Batter

In a mixing bowl whisk 1 egg until lightly beaten. Add 1/2 cup milk and 1/2 cup cold beer or sparkling water; whisk to combine. Gradually whisk the dry flour/cornstarch mixture into the wet ingredients until a smooth, slightly thick batter forms. If the batter is too thick to coat smoothly, add 1–2 tablespoons cold water to reach a paint-like consistency (it should cling to the onion but drip slightly).

Heat Oil

Pour about 3–4 cups of vegetable oil into a large heavy-bottomed pot or deep skillet, leaving at least 2 inches headspace. Heat the oil over medium-high heat until it reaches 350°F (175°C). If you don't have a thermometer, test with a small drop of batter — it should sizzle and rise immediately without burning.

Batter and Coat

Working in small batches (3–4 rings at a time), dredge onion rings first in the 1/2 cup flour, shaking off excess. Dip each ring into the batter to coat completely, allowing excess to drip back into the bowl. Press the battered ring into the panko crumbs, coating both sides and pressing gently so crumbs adhere. Place coated rings on a wire rack while you continue.

Fry

Carefully lower 3–4 coated rings into the hot oil; do not overcrowd. Fry until golden brown and crisp, 2 1/2 to 3 1/2 minutes, turning once midway. Use a slotted spoon or spider to transfer rings to a paper towel-lined tray or wire rack to drain. Immediately season lightly with a pinch of salt. Repeat with remaining rings, keeping cooked rings warm in a low oven (200°F / 95°C) if desired. You will get approximately 10 large crispy rings from the ingredients; smaller rings may yield more pieces.

Final Checks

Let oil return to 350°F between batches for consistent frying. Serve rings hot and crisp; if they sit they will soften, so time frying to finish just before serving.

In-House Dipping Sauce

In a small bowl combine 1/2 cup mayonnaise, 2 tablespoons ketchup, 1 teaspoon Dijon mustard, 1 teaspoon hot sauce, 1/2 teaspoon smoked paprika, 1 teaspoon honey and 1 teaspoon fresh lemon juice. Stir until smooth. Season with 1/8 teaspoon salt and 1/8 teaspoon freshly ground black pepper; taste and adjust seasoning or heat to preference. Chill at least 10 minutes to let flavors meld before serving.