Peel onion and slice about 1/4 inch thick; separate into rings.
Cover with cold water and let stand for 30 minutes. Drain and
spread out on paper towels. Make batter. Sift flour, salt and
baking powder in bowl and set aside. Beat egg yolk slightly; stir
in milk and vegetable oil. Add to flour mixture; stir until smooth.
Beat egg white until stiff peaks form; fold into batter.
1 inch of shortening in saucepan to 375° F..
Dip onion rings in batter;
let excess batter drip off. Drop several rings at a time into
hot fat and fry until golden. Drain on paper towel.
Recipe adapted from Telephone Pioneers Cookbook - Mississippi