Mix sourdough starter, 3/4 cup water, and rice or oat flour together and cover loosely. Let sit at room temperature overnight. Mixture will be very thick and bubbly in the morning.
In the morning add maple syrup, baking powder (if using), salt, eggs, melted butter, and vanilla to the starter mixture.
Stir together until thoroughly combined. Dissolve baking soda in thetsp. of water and stir into batter. Do not stir any more at this point. Ladle onto a hot waffle iron that has been brushed with coconut oil and cook to desired crispness.
