In a large mixing bowl, whisk together the flour, turmeric, and salt. Add the cold butter and cut it into the flour using a pastry cutter or your fingers until the mixture resembles coarse crumbs. Gradually add ice water, mixing just until the dough comes together. Form it into a disk, wrap in plastic, and chill in the fridge for at least 30 minutes.

In a skillet over medium heat, sauté onions, garlic, and scallions in a splash of oil until softened—about 3 minutes. Add the ground beef, breaking it up with a wooden spoon as it browns. Stir in thyme, allspice, paprika, salt, pepper, and the Scotch bonnet pepper. Cook until the beef is no longer pink.

Add soy sauce, ketchup, and beef broth. Simmer for 5 minutes, then stir in the cornstarch slurry to thicken. Let the mixture bubble gently until thickened and cohesive. Remove from heat and let cool.

Preheat oven to 375°F (190°C). Roll out the chilled dough on a floured surface to about ⅛-inch thick. Use a bowl or cutter (6-inch diameter) to cut circles from the dough.

Spoon 2-3 tablespoons of the cooled beef filling into the center of each dough circle. Fold over into a half-moon and crimp the edges with a fork to seal. Place on a parchment-lined baking sheet and brush with egg wash.

Bake for 25 minutes, or until the patties are golden brown and crisp on the outside. Allow to cool for a few minutes before serving—they will be piping hot inside!