Mix wet ingredients: In a large bowl, whisk together the sourdough starter, egg, milk, melted butter, and vanilla extract until smooth.
Combine dry ingredients: In a separate bowl, mix the flour, sugar, baking powder, baking soda, and salt.
Form batter: Gradually add dry ingredients to wet ingredients, stirring gently until just combined. Avoid overmixing to keep pancakes fluffy.
Heat skillet: Preheat a non-stick skillet or griddle over medium heat. Lightly grease with butter or oil.
Cook pancakes: Pour ¼ cup of batter onto the skillet for each pancake. Cook for 2-3 minutes until bubbles form and edges set. Flip and cook for 1-2 minutes until golden brown.
Serve: Stack pancakes and serve warm with toppings like maple syrup, fresh berries, or whipped cream.