In a bowl combine flour, baking powder and salt. Set aside. Separate egg yolks and whites. In a medium bowl, beat egg yolks, then stir in milk, oil and orange zest. Beat the egg whites in a medium bowl until stiff but not too dry.
Pour egg yolk mixture all at once into dry ingredients and stir only until blended. Fold the whipped egg whites gently into the flour/egg batter. Heat waffle iron, and spray with oil so waffles won't stick to iron. Some no stick waffle irons may not need the oil spray.
Pour enough batter into waffle iron so as not to overflow iron when lid is closed.