First, combine the egg whites, cream of tartar and sea salt in a medium bowl and whip until soft peaks form.
Next, combine the egg yolks, maple syrup, milk, vanilla, and melted (and cooled) butter in a large bowl and mix well.
Add the sourdough starter and baking powder and mix gently.
Start heating your pan. I use my second largest burner on medium heat, but you may need to play around with your pan/burner/heat combo.
Finally, fold in the egg whites.
When your pan is fully heated, add a little butter to each hole and then fill each with about 1/4 cup of batter. If you are adding chocolate chips or jam, so this right after you have filled the holes.
Wait about a minute and then use the wooden skewer to turn the pancakes just about a 1/4 turn. It is sort of a twisting motion.
After a little more time, turn the pancakes with the skewer again. You will repeat this until the pancake is fully upside down (and round).
Once they are cooked, remove that batch of pancakes (I use the skewer to this as well) and start a new batch.
They take practice to make, but they are worth it!