These waffles have no sour taste. The flavor is more like a cheap airy ice cream cone, except that you can taste the baking soda. With three leaveners (starter, egg whites, baking soda) they are basically guaranteed to rise. But if you're going to go to the trouble of an overnight recipe, look for any other yeast-only recipe and you'll get more flavor. Martha herself would never serve these - if she had ever used this recipe herself, it would never have left her kitchen.