Heat skillet over medium heat.: Warmth creates the right crust and interior texture, with a faint buttered aroma rising as the pan approaches temperature. You will often hear a soft hiss the moment batter hits the surface, and that sound is a good indicator the pan is ready. If the skillet is too hot, pancakes will brown too fast and remain raw inside, so watch carefully and adjust to medium if you see rapid smoking. A common error is overheating at the start, which leads to dark edges and uncooked centers; keep patience and aim for a steady medium heat.
In a mixing bowl stir together buttermilk, baking soda, and juice and zest of lemon. Add egg, vanilla, and melted butter and stir to combine. In a separate large mixing bowl stir together flour, salt, baking powder, and sugar.: The wet mix will smell citrusy and slightly tangy, and when the baking soda meets the buttermilk and lemon juice you may notice tiny bubbles forming, which is a good sign of lift. The dry bowl should be lightly aerated and free of clumps, with the baking powder evenly dispersed. Combining wet and dry in separate bowls ensures even distribution and prevents overmixing, which can make pancakes tough. Avoid whisking vigorously after combining to keep the texture tender; gentle folding is best.
Pour wet mixture into dry ingredients and stir just until combined. There may be some lumps--don't over-mix the batter. (Add a little splash of buttermilk if the mixture is too thick). Gently stir in blueberries.: The batter will look slightly lumpy and glossy, and those small lumps signal a tender crumb. If it feels too stiff, a tablespoon or two of extra buttermilk will loosen it without thinning too much. When you fold in the blueberries , you should see pockets of color, and the batter will become speckled. Overmixing activates gluten and yields dense pancakes, so stop as soon as the flour streaks disappear. One pitfall is adding too many extra liquids, which can make pancakes spread thin and cook unevenly, so add sparingly.
Grease the warm skillet with butter or non-stick cooking spray. Use a 1/4 measuring cup to spoon the batter onto the pan. Cook until the bottom of the pancakes are golden and bubbles come to the surface. Flip to the other side and cook until golden.: The greased skillet will sizzle gently when batter meets it, releasing a delicious toasted butter scent. As the pancakes cook, look for even golden browning at the edges and a network of bubbles across the top that have started to set, which signals the right flip moment. After flipping, the second side will cook faster, developing a uniform golden color. A frequent mistake is flipping too early, which leads to broken pancakes; wait for the bubbles to set and edges to look dry before turning.
Serve with your favorite pancake syrup.: Once plated, the pancakes should steam lightly and smell richly of citrus and warm grain. A drizzle of syrup or a pat of softened butter enhances shine and mouthfeel, and the contrast between syrup sweetness and the lemon brightness is delightful. To keep stacks warm while finishing the batch, place them on a low oven rack; avoid stacking them too high or steam will collapse the texture. Serving directly from the skillet can be tempting, but using a warm plate keeps them from getting soggy quickly.