Heat half of the water to lukewarm, 105 F - 110 F. Dissolve the yeast in the water with a pinch of the sugar from the recipe; let stand 5 to 10 minutes until the mixture begins to foam.
Put the flour and salt into a large bowl; stir to blend and reserve. Add the egg yolks, one of the egg whites and remaining sugar to the yeast mixture; stir to blend. Add the remaining water, milk, melted butter, oil and vanilla; stir until the mixture is smooth.
Beat the egg whites until stiff peaks form. Fold the egg whites gently into the batter. Let the batter stand for 1 hour, stirring every 15 minutes.
Preheat the Waring Pro Belgian Waffle Maker on setting #4. Use a heat-proof spatula to spread the batter evenly over the grids. After cooking, waffles can be kept warm in a 200 F oven arranged on a baking sheet.
Makes 10 waffles.
Recipe courtesy of Waring.