Start by preheating your waffle iron according to the manufacturer’s instructions.
In a large mixing bowl, whisk together the flour, sugar, baking powder, baking soda, and salt until well combined.
Combine Wet Ingredients: In another bowl, mix the sourdough discard, buttermilk, eggs, melted butter, and vanilla extract until smooth.
Pour the wet mixture into the dry ingredients and gently fold until just combined. Be careful not to overmix; a few lumps are perfectly fine.
Lightly grease the preheated waffle iron with melted butter. Pour in the recommended amount of batter (usually about 1/2 to 2/3 cup, depending on your waffle iron) and close the lid. Cook until golden brown and crisp, usually 5-7 minutes.
Carefully remove the waffles and serve immediately with your favorite toppings, such as syrup, fruit, or whipped cream.