In a medium mixing bowl, mix together the flour, salt, cinnamon and the optional sugar.
Separate the egg whites from the yolks. Add the egg yolks to the flour in the bowl and mix in well.
Mix the sourdough starter into the flour and egg yolk mixture and then add enough raw milk to make a fairly thick pancake batter. Mix everything well until the batter is smooth, with no lumps.
Peel the apples, then with a sharp paring knife cut the apple into small thin slices. You want the slices to be quite thin so they are fast to get cooked through.
Place the egg whites into a dry bowl or large measuring cup and beat with a pinch of salt until stiff peaks form. Add the beaten whites into the pancake batter and mix in gently, until partially combined. There should be plenty of unmixed egg whites visible in the mix - don't overmix or the pancakes won't be fluffy.
Heat up a few tablespoons of coconut oil in a large frying pan and place 3 or 4 spoons of pancake batter on the hot pan. Add some of the unmixed egg whites on top of each pancake. Fry the pancakes on medium heat for 2-3 minutes on each side.
Transfer the cooked pancakes to a serving platter and serve hot with a dollop of whipped cream or some raw honey drizzled on top.