I start these in my food processor because it is so fast but they can be made just as easily in a large bowl by cutting the butter in with a pastry blender or just rubbing it into the dry ingredients using your hands.
In a food processor, combine the flour, sugar, baking powder and salt.
Cut in the butter until mixture resembles a coarse meal.
Transfer to a large bowl and make a well in the center of the dry mix.
Mix together the lemon juice, vanilla, milk and 1 egg.
Pour into the well and mix only enough to form a dough ball.
Roll to 1 inch thickness and cut out biscuits with 3 inch biscuit cutter and place on parchment lined baking sheet.
Whisk together the egg and water to make an egg wash and lightly brush the tops of the biscuits with it. You will only use a small amount of the egg wash.
Sprinkle turbinado sugar on top of the biscuits.
Bake at 375 degrees F for 20 minutes or until golden brown.