Mix flour, turmeric, curry powder and salt in a large bowl. Add the butter and use a pastry cutter or two blunt knives to work the butter into the dry ingredients until the mixture resembles crumbs. Pour the water into the butter/flour mixture and mix thoroughly. Gather the dough into a ball. If dough doesn't stick together, add water, 1 tablespoon at a time, until a ball can be formed. Kneed the dough on a lightly floured surface for a few times. Wrap in plastic wrap and place in the refrigerator to chill.
Heat the oil in a large skillet over medium heat. Add the onion and cook for 3 minutes, until tender. Add the carrot and bell pepper and cook for another 2 minutes. Add allspice and paprika, tossing to coat vegetables. Stir in ground beef. Season with curry powder, garlic powder, dried thyme, sugar, salt, and pepper. Cook, stirring and breaking up any lumps with wooden spoon, until the meat is nearly cooked through. Stir in the flour and panko bread crumbs. Add the water, and cook a few minutes more, until the liquid is absorbed. It should not be watery, yet still remain moist. Stir in chopped scallion. Remove from heat and set aside to cool.
Preheat the oven to 375 degrees. Divide the dough into 5 equal sections. Roll each section into a 6-7 inch circle (approximately 1/8 inch thick). Place about 1/4 cup of meat filling in the middle of a pastry and moisten edges of each circle with a little water. Fold over and press edges together, making a half circle. Use a fork to press edges, and brush the top of each patty with beaten egg yolk. Place on a parchment-lined baking sheet.