Preparation / Directions:
Preheat over to 350 degrees. Spray a 13-9 inch baking pan with nonstick cooking spray.
In a large bowl, with an electric mixer at medium speed, beat the granulated sugar, yogurt, egg whites, vanilla and vinegar until fluffy, about 2 minutes. With the mixer at low speed, gradually add the flour mixture; stir until just combined (do not overmix). Add 2 cups water and stir until just smooth.
Pour the batter into the pan. Bake until a toothpick inserted in the center comes out clean, about 40 minutes. cool completely in the pan on a rack. Dust with confectioner's suga