Preheat your waffle iron. If using a cast iron or aluminum waffle maker, lightly grease it with oil so the waffles do not stick.

In a large bowl, whisk together the flour, sugar, salt, and baking soda.

In a medium bowl, whisk together the buttermilk, melted butter, sourdough starter, and eggs. Pour into the flour mixture and whisk until only a few small lumps remain. The batter should pour from a spoon but not be runny; if too thick, thin with a little water, one tablespoon at a time.

Cook the batter in your hot waffle iron until done to your liking. Serve hot with maple syrup and chopped fresh berries.

The night before, in a large bowl combine the buttermilk and melted butter. Add the sourdough starter and whisk thoroughly. Sprinkle the sugar over the top, add the flour, and whisk to incorporate. If very thick, add a little more buttermilk. Cover and let sit at room temperature overnight (refrigerate if your kitchen is warmer than 72°F/22°C).

In the morning, preheat and lightly grease your waffle iron. The batter will have risen and show signs of fermentation. Sprinkle the salt and baking soda on top.

Lightly beat the eggs in a small bowl and pour into the fermented batter. Gently stir until incorporated.

Cook the batter in your hot waffle iron until done to your liking. Serve hot with maple syrup and fresh berries.