Preheat the waffle maker according to the manufacturer's directions.
In a large mixing bowl, whisk together the flours, sugar, salt, baking powder, and baking soda, breaking up any clumps.
1 cup all purpose flour, ½ cup whole wheat flour, 2 tablespoons granulated sugar, ½ teaspoon kosher salt, 1 teaspoon baking powder, ½ teaspoon baking soda
In a separate bowl, whisk together the sourdough starter, eggs, buttermilk, and melted butter. Pour the dry ingredients into the wet and gently stir together until just combined. It is okay if there are still some small lumps, overmixing will result in tougher waffles.
1 cup sourdough starter (if you don’t have your own, many bakeries have plenty on hand to sell or even give you if asked), 2 eggs, ¾ cup buttermilk, 3 tablespoons unsalted butter, divided
Drop the batter into the preheated waffle iron (¼ to ½ cup dollops, depending on the size of the iron) and cook according to the manufacturer’s directions, 3 to 5 minutes per waffle. Serve immediately with desired toppings.