Sweet Vidalia Onion Rings with Chili Catsup

Ingredients

• 2 cups (10 oz) all-purpose flour
• 1 teaspoon baking powder
• 2 cups (16 fl oz) beer, at room temperature
• 1 teaspoon salt, plus salt to taste
• 1 teaspoon freshly ground pepper
• 4 egg whites, at room temperature
• 2 1/2 cups (10 oz) fine dried bread crumbs
• peanut oil for deep-frying
• 3 extra-large Vidalia onions (or Maui or Walla Walla or other sweet onion), cut crosswise into slives 3/4 inch (2cm) thick and separated into rings