Peel onions. Cut into ⅛-inch-thick slices. Separate slices into rings. Place in ice water for 10 minutes. Remove and dry rings on paper towels.
Combine flour and baking powder in a plastic bag. Heat oil in French-fryer. Put 6 rings into the bag at a time to coat evenly with flour. Drop into oil heated to 390 degrees. When brown, lift out and drain on paper to