~from Savoring Time in the Kitchen
This recipe can be halved for 2 people...Half of one large egg is 1/8 cup of beaten egg.
If you don't have a sourdough starter, you could substitute plain, Greek yogurt with active yogurt cultures (such as Fage, Chobani, etc) for the starter in the recipe below.
For the overnight sponge:
1 cup (240 grams) unfed sourdough starter
1 cup (224 grams) buttermilk (if you don't have buttermilk, just add 1 tablespoon white vinegar or fresh lemon juice to 1 cup milk)
1 cup (120 grams) all-purpose flour or a mixture of AP and whole wheat flour
1 tablespoon (about 13 grams) light brown sugar
For the morning batter:
1 large egg, lightly beaten
2 tablespoons melted butter or neutral oil (coconut oil would be a great choice)
½ teaspoon vanilla extract
½ teaspoon (3 grams)salt
1 teaspoon (6 grams) baking soda
Pour the sourdough starter into a large bowl and add the buttermilk, flour and sugar, then stir to combine. Cover the bowl and allow it to rest overnight on the kitchen counter.
The next morning, preheat a waffle iron or large frying pan. Whisk the egg, melted butter (or oil) and the vanilla extract together in a medium bowl, then add the rested sponge. Add the salt and the baking soda to the batter and mix to combine.
Spray the waffle iron or frying pan lightly with nonstick cooking oil.
Pour some batter onto the preheated waffle iron and cook until the waffle is brown and crisp and repeat with remaining batter. For pancakes, pour a small ladle-full of batter on a preheated pan or griddle, flipping them when they are well browned on the bottom. Serve immediately.
Adapted from King Arthur Flour and the New York Times