Add the cherries and sugar to a small saucepan over medium-high heat. After a minutes or two, the cherries with release their juices. Bring to a boil and cook 10 minutes, stirring occasionally to break up the fruit. Add the pomegranate juice and arrowroot to a small bowl or measuring cup. Stir to dissolve. Add to the cherries and boil 2 minutes, or until the mixture thickens. Remove from heat and stir in almond extract. Let cool completely.

Heat oven to 400F. Cut the puff pastry into 9 squares. Spoon 1 heaping teaspoon of preserves into the center of a pastry square. Fold into a triangle and crimp edges with a fork, or add another half teaspoon filling and bring the four corners of the pastry to meet in the middle (see photo above). Place on a baking sheet. Repeat with remaining pastry and filling.

In a small bowl, whisk together the egg yolk, water, and vanilla bean pulp. Brush over the tops of the pastry. Bake 8-10 minutes, or until golden brown. Let cool before serving.