Remove your sourdough starter from the refrigerator. Stir the starter to mix in any liquid that has risen to the top.
In a large mixing bowl, mix together the 1 cup of starter and the buttermilk. Add all of the flour, and the sugar to the bowl and mix well.
Cover the bowl loosely with plastic wrap and let sponge proof in a warm location overnight.
Making the waffle batter
Preheat the waffle iron following the manufacturers directions.
In a small bowl beat the eggs and oil together.
Add the eggs, oil, salt and baking soda to the bowl of sourdough sponge. Mix until combined. The batter should begin to bubble slightly.
Brush the waffle iron with vegetable oil.
Fill the hot waffle iron with the waffle batter and cook following the manufacturers directions.
Cook the waffles until golden brown. Repeat with remaining batter.
Place the hot waffles in a single layer on a wire rack while cooking the remaining waffles. This will keep the waffle crisp.
about 8 large Belgian style waffles.
Video
Recipe Expert Tips
Making the sponge: Mix the sponge ingredients early in the morning the day before you plan on making the waffles for breakfast.
Proofing the sponge: Place the bowl in a warm spot like inside a cold oven with the light turned on.
Filling the waffle iron: Do not over fill the waffle iron. The batter will sqeeze out of the waffle iron and make a huge mess.
Crispy waffles: The trick to making sourdough waffles that are crispy on the outside but still tender on the inside is to place the cooked waffles on a wire rack. Do not stack the waffles on top of each other until you are plating them. The heat from the hot waffles will cause the golden outside to soften.