Combine flour, sugar, salt, baking powder, and baking soda in a large bowl.
In a separate smaller bowl, combine the egg yolk, buttermilk, and milk. Stir together to mix. Add the melted butter and whisk until well combined.
Pour the milk mixture into the flour mixture and stir until just combined. Add the egg white (no whisking needed) and stir together to make a thick batter. (Do not over-mix. Small lumps provide pockets of air that lift the pancakes to heavenly fluffiness.) Set batter aside for 5 minutes.
Heat a large skillet over medium-high heat. When hot, lightly brush canola oil over pan. After about 20 seconds, when the oil just starts to shimmer, lower the heat to medium-low and drop in 2-3 spoonfuls of pancake batter for each pancake.
Cook for about 2 minutes. When the batter gets bubble-y, it's close to flip time. Lift up an edge of one pancake to see if it's golden brown, then flip and cook on the other side for 2 to 2 more minutes.
Remove to plates and serve with your favorite toppings or hot maple syrup.
Note: If you want to add blueberries or chocolate chips to the recipe, just drop them in when you add the milk mixture to the flour.