In a large bowl whisk together the flour, baking powder, baking soda, salt, and sugar.: The aroma of combined dry leaveners is subtle but important, they create a faint mineral scent that becomes toasty as pancakes cook. Mixing these ingredients first ensures even distribution so you do not get pockets of baking soda which can cause odd flavors. I sift or whisk thoroughly so clumps disappear, and I can tell the mixture is right when the color and texture are uniform. A frequent mistake is stirring wet and dry together too vigorously, which can develop gluten and produce chewy pancakes. If you notice streaks of white, keep whisking until smooth, but do not overwork the mixture before adding liquids.
In a medium bowl or liquid measuring cup, combine the sourdough starter, milk, eggs, and butter and whisk until combined. Pour the wet ingredients over the dry and mix until just combined. It should still be a little lumpy.: You will see a shiny, cohesive batter form that smells faintly tangy and creamy, with a soft sheen from the melted butter . Whisking the wet ingredients first helps break up the starter so it incorporates evenly. When you fold wet into dry, stop when a few small lumps remain; those little lumps reduce gluten formation and keep the pancakes tender. If you overmix the batter, it will tighten and lead to tougher pancakes, so resist the urge to make it perfectly smooth. A common pitfall is adding too much liquid to correct lumps, which thins the batter excessively and causes thin, flat pancakes.
From here you have the option to cook the pancakes right away, or you can cover the dough and leave it on the counter overnight to ferment and have more of a distinct sourdough flavor.: The surface of the batter will appear slightly aerated if you let it rest, and the aroma grows more complex, almost vinous in a pleasant way. Overnight fermentation allows enzymes to break down starches for deeper flavor and better browning. If you cook immediately you will still get tasty pancakes, but the overnight option delivers the signature tang. Watch out for leaving it out too long in very warm kitchens, which can overproof and thin the batter excessively, so refrigerate if you need to pause beyond a safe time window.
On a griddle preheated to 325°-350° and sprayed with cooking spray, pour 1/3 cup pancake batter on and cook until bubbling on top, about 2 minutes. Flip and cook for an additional 1-2 minutes, or until golden brown on the bottom.: When the batter hits the hot surface you should hear a soft sizzle and see small bubbles gather across the top; those bubbles signal that the interior is setting. The edges will start to look matte rather than glossy, another sign that it is time to check. Cooking at a steady medium heat ensures the inside cooks through while the exterior colors up evenly. A too hot griddle will brown the outside before the center cooks, producing an underdone middle, so regulate temperature and do a test pancake first.
Serve with your favorite pancake toppings and enjoy.: After flipping you will notice a warm, toasty smell and a pleasing golden hue on the cooked side, with the underside having an even color. The sound will be quieter after flipping, and the pancake should feel springy when gently pressed. This short second cook finishes the interior while sealing in moisture. Overcooking at this stage dries the pancake, so remove them when they are just set and still tender.
Serve with your favorite pancake toppings and enjoy.: The first bite should offer a balance of tang, light sweetness, and tender crumb, with a hint of buttered richness. I like to serve stacks hot so steam rises and the texture remains soft. If you are preparing for a crowd, hold them in a warm oven to keep consistent temperature. A mistake to avoid is stacking straight from skillet to plate without a brief rest which can make the bottoms soggy from trapped steam, so give them a moment to breathe if you plan to stack high.