The night before you want to eat waffles for breakfast, get out your sour dough starter, stir it up, and measure 1 cup into a large bowl. Add 1 cup water and 1 cup flour to the remaining starter (you may have to transfer it to a large bowl, too) and leave it out over night to regenerate. To the original 1 cup starter, add the buttermilk, flour, and sugar, and mix well. Go to bed. In the morning, put the regenerated starter away in the fridge, and then separate the eggs, placing the yolks in a small bowl or measuring pitcher and the whites in the bowl of an electric mixer, where you can beat them until stiff. Start heating your waffle iron the same time as you start beating the whites. Add the oil, vanilla, soda, and salt to the yolks, mix, and add to the starter mixture from last night, then fold in the whites. Bake in your waffle iron. Makes a lot! (9-12 regular waffles)
Sourdough starter is a fermented mixture of natural yeasts, flour, water. Sour dough starter, like all yeasts, needs to be fed and cared for. One commonly passed-around recipe, called Amish Friendship Bread, or sometimes Herman, is actually a sourdough starter, made with milk and sugar. Because it has so much milk and sugar, it is a little temperamental, so I recommend a simpler variety, made with water, yeast, and flour.
To make a starter, pour 1 cup warm water into a bowl (water that has had potatoes boiled in it is the traditional thing to use), sprinkle 1 tsp. yeast over it, mix, and let stand a few minutes until yeast dissolves. Add 2 tsp. sugar and 3/4 cup to 1 cup flour, and mix. Let the starter sit on the counter for 5 days (uncovered, or draped with cheesecloth, if you can't stand to leave it completely uncovered) so the natural yeasts loose in your kitchen get in there. Stir it daily. It should start to bubble and smell nicely sour. On the 5th day feed the starter with another 3/4 to 1 cup flour and 1 cup water. It is ready to use the next day. It can be refrigerated indefinitly, but works best if you get it out, and use some and feed the rest (as described in the waffle recipe) at least once a month.