Beer-Battered Onion Rings

INGREDIENTS

• 2 sweet onions, peeled and sliced into ½-inch rounds
• 3 cups beer, divided
• 2 teaspoons malt vinegar (can substitute cider vinegar)
• 1 teaspoon salt, divided
• ¾ teaspoon black pepper, divided
• 2 quarts peanut oil (can substitute vegetable oil)
• ¾ cup all-purpose flour
• ¾ cup cornstarch
• 1 teaspoon baking powder
• Salt & freshly ground black pepper, to taste