In a medium sized bowl add milk and yogurt. Stir in sourdough starter until fully dissolved.
Whisk in flour and sugar, cover and let sit on a counter for about 30 minutes.
Whisk in melted butter, baking powder, salt, baking soda and vanilla extract.
Beat egg yolks with hand held mixer for 3-4 minutes on high speed until thick and lemon colored. Whisk into the batter.
With clean beaters mix egg whites and cream of tartar to stiff peaks. Fold carefully into the batter keeping it light and fluffy, and just before baking pancakes.
Bake on a pancake griddle at 218ºC (425ºF) about 3 minutes on one side and 1 1/2 minutes on the other side. Flip the pancake once you see bubbles coming out on the surface of pancake.
Serve warm with maple syrup and fresh or frozen fruits.