Add all-purpose flour, baking powder, sugar, baking soda, and salt into a large bowl. Whisk to combine thoroughly.

In a second bowl add the egg yolk and with a whisk break it up and stir it well. Add buttermilk and vegetable/canola oil to the bowl with the whisked egg yolk and combine your wet ingredients to combine. 

Once these wet ingredients are combined fully, add all of the sourdough starter and whisk again to incorporate.

Add your wet ingredients into the bowl with your dry ingredients and stir just long enough that you no longer see dry flour. This batter does not need to be smooth a few lumps are ok.

In a third bowl (or wipe out and use the first dry ingredient bowl) add egg whites and beat with a whisk until stiff peaks form. This is going to take some real elbow grease. If you have a stand mixer or electric hand mixer, you will want to pull it out for this process, but you can do it by hand. Just keep whipping and eventually, the egg whites will stiffen.

Carefully add the whipped egg whites to the bowl with the rest of the batter. Carefully fold the batter over the egg whites to combine. The goal here is to combine without losing a lot of the air that you whipped into the egg whites. This will keep your pancakes super light and fluffy. 

Leave the bowl on the counter while you prep your griddle or large pan. 

I typically use a 1/4 or 1/3 cup measure to scoop out my pancakes onto a griddle. You can go bigger or smaller. 

Set your pan or griddle over medium-high heat. Add a teaspoon or so of butter to the pan/griddle while it heats up, once the butter is melted add a scoop of pancake batter. 

Cook each pancake until you start to see bubbles appearing on the uncooked side of the pancake. Once you start to see those bubbles, you can flip. Using a spatula I sometimes will peek under the pancake just to see the level of browning achieved before flipping.

Cook for another couple of minutes on the second side.

Once your pancake is cooked on both sides, remove from the heat to a sheet pan or cookie pan and place in a 200-degree oven to keep pancakes warm until the rest are finished cooking.

Once they're all done, add butter and your favorite maple syrup and serve.