Fried Onion Rings
["2 large sweet onions", "1 egg", "2/3 c. water", "1 Tbsp. vegetable oil", "1 tsp. lemon juice", "1 c. all-purpose flour", "1 1/2 tsp. baking powder", "1 to 1 1/4 tsp. salt", "1/8 to 1/4 cayenne pepper", "oil (for deep-fat frying)"]
["Cut onions into 1/2-inch slices; separate rings. Place in a bowl; cover with ice water and let soak for 30 minutes."]
["sweet onions", "egg", "water", "vegetable oil", "lemon juice", "flour", "baking powder", "salt", "cayenne pepper", "oil"]