In a large mixing bowl, whisk together the plain flour, salt, and ground turmeric until well combined. Using a pastry cutter or your fingers, cut the frozen butter and shortening into the flour mixture until it resembles coarse crumbs. Gradually add icy cold water, one tablespoon at a time, mixing until a dough forms. Wrap the dough in plastic wrap and refrigerate for 30 minutes to ensure it is cold and pliable.

In a large skillet over medium heat, brown the minced beef until fully cooked, about 5-7 minutes. Drain any excess fat, then add chopped onions and minced garlic, cooking until the onions are translucent, roughly 3-4 minutes. Stir in thyme leaves, cayenne pepper, Jamaican curry powder, beef stock, and soy sauce. Allow this mixture to simmer until thickened, about 10 minutes. Remove from heat, stir in the breadcrumbs, and let it cool completely.

Preheat your oven to 190°C (375°F) while you roll out the dough. On a floured surface, divide the chilled dough into manageable portions, rolling each out to about 3mm thickness. Use a round cutter to cut out circles from the dough. Place a generous spoonful of the beef filling on one half of each dough circle. Fold the other half over and seal the edges using a fork, ensuring no filling escapes.

Line a baking tray with parchment paper and arrange the filled patties on it, leaving space between each. For a golden finish, brush the tops with beaten egg or a plant-based alternative. Bake in the preheated oven for 20-25 minutes, or until the patties are golden brown and flaky. Keep an eye on their color as they bake for a perfect finish. Once done, cool the Jamaican beef patties slightly before enjoying them warm!