I am attempting to veganize a Kringle for an upcoming event. Below is the original recipe I am referencing, and I am stumped as to how to replace the egg in the dough portion. I have never seen a pastry dough recipe with an egg included - is it for moisture or is there another reason? Original recipe link

For the Pastry Dough

1 cup all-purpose flour

1 cup bread flour

3 tbsp granulated sugar

2 tsp instant yeast

1 tsp fine sea salt

1 cup unsalted butter, cold, cut into 1/2" pieces

1/3 cup whole milk, cold

 1 egg, large, cold

1 egg white, for egg wash

For the Kringle Filling

1.5 cups pecans, finely chopped

1 cup brown sugar, firmly packed

1/2 cup butter, room temperature

For the Icing

1 cup powdered sugar

1 tsp vanilla extract

1 pinch fine sea salt

For the Salted Caramel Glaze

1/4 cup unsalted butter

1/4 cup granulated sugar

1/4 cup brown sugar, packed

1/2 cup whipping cream

The butter, milk, sugar substitutes are all simple swaps and I have an entirely different caramel glaze recipe to utilize. Soy milk works as a substitute for an egg wash, so that part is covered. All I can think is to substitute the egg in the dough for an equivalent amount of vegan sour cream or silken tofu, if the purpose of the egg in this recipe is for moisture alone? Any assistance or light that could be shed on why the egg is in this recipe would be very much appreciated.

I am attempting to veganize a Kringle for an upcoming event. Below is the original recipe I am referencing, and I am stumped as to how to replace the egg in the dough portion. I have never seen a pastry dough recipe with an egg included - is it for moisture or is there another reason? Original recipe link

For the Pastry Dough

1 cup all-purpose flour
1 cup bread flour
3 tbsp granulated sugar
2 tsp instant yeast
1 tsp fine sea salt
1 cup unsalted butter, cold, cut into 1/2" pieces
1/3 cup whole milk, cold 
1 egg, large, cold
1 egg white, for egg wash

For the Kringle Filling

1.5 cups pecans, finely chopped
1 cup brown sugar, firmly packed
1/2 cup butter, room temperature

For the Icing

1 cup powdered sugar
1 tsp vanilla extract
1 pinch fine sea salt

For the Salted Caramel Glaze

1/4 cup unsalted butter
1/4 cup granulated sugar
1/4 cup brown sugar, packed
1/2 cup whipping cream

The butter, milk, sugar substitutes are all simple swaps and I have an entirely different caramel glaze recipe to utilize. Soy milk works as a substitute for an egg wash, so that part is covered. All I can think is to substitute the egg in the dough for an equivalent amount of vegan sour cream or silken tofu, if the purpose of the egg in this recipe is for moisture alone? Any assistance or light that could be shed on why the egg is in this recipe would be very much appreciated.