1. 1. Prepare the Dry Ingredients: In a large mixing bowl, whisk together the all-purpose flour, granulated sugar, baking powder, baking soda, and salt. Make sure there are no lumps and the ingredients are well combined.

2. 2. Combine the Wet Ingredients: In a separate medium bowl, whisk together the buttermilk, sourdough starter, egg, melted butter, lemon zest, and vanilla extract until smooth. The mixture should be uniform in color and consistency.

3. 3. Mix Wet and Dry: Pour the wet ingredients into the dry ingredients. Stir gently with a spatula or wooden spoon until just combined. It’s okay if there are a few small lumps; overmixing can lead to tough waffles.

4. 4. Fold in Blueberries: Carefully fold in the fresh or frozen blueberries. Distribute them evenly throughout the batter without crushing them too much.

5. 5. Preheat Waffle Iron: Preheat your waffle iron according to the manufacturer’s instructions. Lightly grease the plates with a little melted butter or cooking spray, even if it’s non-stick, to ensure the waffles release easily.

6. 6. Cook the Waffles: Pour about 1/2 to 3/4 cup of batter onto the hot waffle iron, depending on its size. Close the lid and cook for 3-5 minutes, or until the waffle is golden brown and crispy, and steam stops escaping.

7. 7. Serve Warm: Carefully remove the cooked waffle from the iron using a fork or tongs. Repeat with the remaining batter. Serve immediately with your favorite toppings.