Make sure your sourdough starter is active by feeding it a few hours before making the overnight batter.
In a large 4 quart glass mixing bowl, measure in the starter, Greek yogurt, milk, and honey. Whisk well, cover with plastic wrap, poke a few small holes, and set aside in a warm and draft-free area overnight.
In the morning, your batter should be active and bubbly. Whisk in the room temperature eggs, butter, vanilla, baking powder, and baking soda (make sure these are free of clumps).
Grease the waffle iron and start cooking until golden brown.
Serve hot with toppings of your choice or cool on cooling rack then freeze in a single layer before storing in an airtight container in the freezer for up to 3 months.
