In a large bowl, whisk together the sourdough starter, milk, egg, melted butter, vanilla extract (if using), and sugar until well combined and smooth.
In a separate bowl, mix the flour, baking powder, baking soda, and salt. Whisk to evenly distribute the leaveners and salt through the flour.
Pour the dry ingredients into the wet mixture. Gently stir until just combined—it’s okay if the batter is a little lumpy. Avoid over-mixing to keep the pancakes light and airy.
Heat a non-stick skillet or griddle over medium heat. Lightly grease if needed. Drop batter by ¼ cupfuls onto the pan. Cook until bubbles appear and the edges look dry (about 2–3 minutes), then flip and cook the other side for 1–2 minutes until golden. Serve immediately with your favorite toppings.
