Have your fed sourdough starter ready.
In a medium bowl, combine the wet ingredients.
Add the flour and sugar, if using. You can use this batter immediately or let it sit (ideally overnight).
When you're ready to make your waffles, preheat your cast iron waffle maker over medium heat.
Once your waffle iron is hot, grease it with oil. Allow the oil to become hot.
Add your batter to the waffle iron. Bake your waffle, flipping the waffle iron after a few minutes. Resist the temptation to try to lift the upper part too soon. When the waffles are done, they will not stick and come out easily.
Keep warm until ready to eat. Serve with a dollop of soft butter and maple syrup of your favorite toppings.