Sift the flour, sugar, baking powder, baking soda and salt into a large mixing bowl. In a separate large bowl, lightly whisk the eggs. Add the milk, sour cream, half the melted butter and the vanilla, whisking to blend. Make a well in the dry ingredients and pour the egg mixture into it. Whisk the ingredients together just until blended. Fold the blueberries and lemon zest into the batter.

Heat a large skillet or griddle over medium heat and coat with some of the remaining melted butter. For each pancake, pour about 1/4 cup of the batter into the hot skillet. Cook 3 or 4 pancakes at a time, depending on the size of the skillet. If the batter seems too thick, thin it with 1 to 2 tablespoons milk. When bubbles begin to form and "pop" on the pancake's surface, after about 1 minute, and the outer edge looks done, flip it over and cook briefly for about 30 seconds on the other side.