Place the ground beef in a skillet and bring over medium heat. Cook, breaking up with a spoon until cooked through and broken into small pieces. Add the tablespoon of water, the taco seasoning and the red pepper flakes and stir together until well combined. Remove from heat and transfer to a mixing bowl. Add the chopped tomatoes and shredded cheddar and stir until combined.

On a clean, dry surface sprinkle a small amount of flour to prevent sticking and lay down your sheet of defrosted puff pastry. Using a rolling pin, roll the pastry into a 13”x13” square of even thickness. Using a knife or pizza cutter, cut the pastry into 9 even squares (3 rows of 3).

Spoon the ground beef filling evenly into the center of each pastry square and spread it a bit diagonally toward two opposite corners. Get a small dish of water and lightly spread a bit of water around the edges of a square. Fold one corner over diagonally to meet its opposite corner and form a triangle. Press the edges of the pastry together to seal the filling inside. You can also press the sealed edges with a fork to form lines along the edge. Repeat with each pastry square. Cover a baking sheet with parchment paper and transfer the triangles to the sheet.

Combine the egg and a tablespoon of water in a bowl and whisk together to combine. Use a pastry brush to brush the egg wash over top of each pastry triangle. Discard leftover egg wash. Sprinkle the ¼ teaspoon of oregano over the tops of the triangles.

Preheat the oven to 400. Place the baking sheet into the freezer or refrigerator for 15-20 minutes to ensure the pastry is chilled (this makes it puff better). Transfer the sheet to the oven and bake for 16-18 minutes until pastry is golden.