Preheat waffle iron.Combine flour, oats, baking powder, sugar, and pecans in a large bowl.Combine egg yolks, milk, and vegetable oil in a separate bowl, and mix well.Add liquid mixture to the dry ingredients, and stir together. Do not overmix; mixture should be a bit lumpy.Whip egg whites to medium peaks. Gently fold egg whites into batter.Pour batter into preheated waffle iron, and cook until the waffle iron light signals it’s done or steam stops coming out of the iron. A waffle is perfect when it is crisp and well-browned on the outside with a moist, light, airy and fluffy inside. (Or make pancakes.)Add fresh fruit and a light dusting of powdered sugar to each waffle, and serve.