Mix the overnight batter. In a large bowl, whisk together starter, flour, and milk until smooth. Cover the bowl tightly (lid, plate, or plastic wrap) and let it rest in the fridge overnight, 8–12 hours. For a stronger tang, you can rest at cool room temperature (around 68°F/20°C) for 6–8 hours.

Finish the batter in the morning. Whisk the egg, sugar, melted butter, and vanilla into the rested mixture. Sprinkle baking powder, baking soda, and salt over the top, then whisk just until combined. The batter should be pourable and slightly bubbly.

Adjust consistency. If it looks too thick (more like cake batter than pancake batter), add 1–3 tablespoons of milk to loosen. If it’s too thin, whisk in 1–2 tablespoons of flour.

Preheat the pan. Heat a nonstick skillet or griddle over medium heat until a drop of water skitters across the surface. Lightly grease with butter or oil. A well-heated pan helps create even browning and a delicate crust.

Pour and cook. Scoop 1/4 cup of batter per pancake. Cook until the edges look set and bubbles form on top, 2–3 minutes. Flip and cook another 1–2 minutes, until golden on both sides.

Serve warm. Stack pancakes on a warm plate and cover lightly with a clean towel while you cook the rest. Serve with butter and maple syrup, fresh berries, or yogurt and honey.