In a large bowl, whisk together the flour, sugar, baking powder, baking soda, and salt. In another bowl, whisk together the milk, melted butter, lemon juice, lemon zest, and egg yolks. Add the wet ingredients to the dry ingredients. Mix together. The batter will be lumpy.
In another clean bowl, whip the egg whites to stiff peaks. Gently fold in batter in three additions. Do not overmix. Batter will not be smooth.
Heat a lightly greased griddle or skillet over medium high heat. Scoop 1/3 cup batter onto griddle. Cook until bubbles form on the surface and the edges of the pancake are set. Gently flip pancake and cook the other side until lightly browned. Repeat with remaining batter. Adjust heat according if pancakes are browning too fast.
Serve pancakes warm with blueberry sauce and salted butter. In a heavy-bottomed sauce pot, add blueberries, lemon zest, and maple syrup. Set over medium high heat. Bring mixture to a simmer. Stir mixture as needed to prevent burning along the edges. Cook until mixture has thickened and about half of the blueberries have burst. Remove from heat and cool to room temperature. Blueberry sauce will thicken as it cools.
Serve blueberry sauce chilled or warmed up over hot pancakes. Store any leftovers covered in the fridge. Will keep in the fridge for a few days.
