1 tbsp. fine sea salt
1 tbsp. freshly ground black pepper
1 tbsp. paprika
1 tbsp. granulated garlic
1 tbsp. sugar
4 large sweet onions, peeled and sliced into 3/4 inch slices
2 cups all-purpose flour
1/4 cup cornmeal
6 large eggs
1/4 cup water
5 cups panko crumbs
6-8 cups canola oil
Combine sea salt and next 4 ingredients; set aside.
Separate onions into rings.
Set aside 3 large shallow bowls. Combine flour, cornmeal and 1 tsp. salt mixture in first bowl. Whisk eggs and water in second. Mix panko and 1 tsp. salt mixture in third.
Dredge each ring in flour mixture, then egg mixture. Dip ring into flour mixture again, then panko mixture, pressing crumbs onto rings to ensure even coating. Place on parchment-lined baking sheet.
Repeat with remaining onions. Cover loosely; chill 30 minutes.
Heat oil to 350 degrees in a large deep skillet or electric fryer (use fry thermometer to ensure oil is not too hot). Fry rings in batches, allowing oil to return to 350 degrees between batches.
Place cooked onions on paper towel-lined baking sheet; sprinkle with 1 tsp. salt mixture.