Sift the flour, baking powder, baking soda, and salt into a large bowl.

In a separate bowl, whisk together the sourdough starter, buttermilk, egg, melted butter, and sugar.

Gradually combine the wet ingredients with the dry ingredients, stirring gently until just combined; a few lumps are fine.

Preheat a non-stick griddle or frying pan over medium heat. Test readiness by sprinkling a few drops of water; they should sizzle and evaporate quickly.

Lightly grease the griddle with butter or oil, spreading it thinly with a paper towel.

Using a 1/4-cup scoop, pour the batter onto the griddle.

Cook until bubbles form and pop on the surface and the edges start to look set, about 2–3 minutes.

Flip the pancakes and cook for another 1–2 minutes until golden brown.

Stack pancakes on a plate, covering loosely with foil to keep warm.

Serve warm with your favorite toppings such as maple syrup, fresh berries, or whipped cream.