Whisk the flour, powdered sugar, baking powder and salt together in a large bowl.
Whisk the soy milk, melted coconut oil, vanilla extract, and egg yolk together in a separate bowl.
Beat together the egg whites + cream of tartar until stiff peaks form (~2min), then stir the milk mixture into the flour mixture until combined.
Gently fold in the beaten egg white mixture.
Ladle ~1/4 cup of batter onto a nonstick skillet and cook for 2-3 minutes or until bottom is golden in color, then flip and cook for ~1 min on the other side.
On a grill pan, add sliced nectarine and cook for a few minutes until softened.
Serve together with maple syrup (if desired).