In medium saucepan, combine cherries, cornstarch, lemon juice, salt, sugar, and water over medium heat until mixture starts to bubble. Turn heat to low and simmer for 10 minutes, stirring frequently.
Remove from heat and add vanilla, lemon zest, and almond extract (optional). Cool for 10-15 minutes before using.
Preheat oven to 375 degrees
Crack egg in a bowl and whisk with a couple teaspoons of water.
Roll out each sheet of puff pastry until about a 12x12 in square. Cut into four squares. Place 2 hefty tablespoons of filling into middle of square. Brush edges of puff pastry with egg wash and fold over to make a triangle. Crimp edges with fork to keep filling from spilling out.
Brush tops with egg wash, sprinkle with turbinado sugar and cut two little slits to help vent.
Bake for 20-25 minutes, or until puff pastry is golden brown.
