Mix Wet Ingredients: In a large bowl, whisk together sourdough starter, milk, egg, melted butter, sugar, and vanilla until smooth.
Add Dry Ingredients: Sift in flour, baking soda, and salt. Gently fold until just combined. Do not overmix; the batter should be slightly lumpy.
Preheat and Grease Pan: Heat a skillet or griddle over medium heat. Lightly grease with butter or oil.
Cook and Flip: Pour 1/4 cup of batter onto the skillet. Cook until bubbles form on the surface and edges look set (about 2-3 minutes). Flip and cook another 1-2 minutes until golden brown.
Serve and Enjoy: Serve warm with your favorite toppings like butter, maple syrup, or fresh fruit.