In a skillet over medium heat, add the ground turkey, minced onion, and bell pepper. Cook until the turkey is browned and cooked through, about 5-7 minutes. Drain any excess fat, then stir in the garlic powder, cumin, kosher salt, chili powder, paprika, oregano, and canned tomato sauce. Mix well and add water to reach your desired consistency. Cook for an additional 2-3 minutes, then remove from heat and let the filling cool slightly.
In a mixing bowl, combine the flour, baking powder, and kosher salt. In another bowl, mix the Greek yogurt until smooth. Gradually add the yogurt mixture to the flour mixture, stirring until a dough forms. Knead gently until smooth, about 1-2 minutes. Cover with a towel and let it rest for 10 minutes.
On a lightly floured surface, roll out the dough to about 1/8-inch thickness. Use a sharp knife or pastry cutter to cut the dough into circles, roughly 4 inches in diameter.
Preheat your oven to 375°F (190°C). Take a dough circle and place about 1 tablespoon of the filling in the center. Brush the edges with the beaten egg, then fold the dough over to create a half-moon shape. Press the edges to seal, and use a fork to crimp the edges for extra security. Repeat with the remaining dough and filling.
Place the empanadas on a baking sheet lined with parchment paper. Brush the tops with the remaining beaten egg for a golden finish. Bake for 20-25 minutes, or until the empanadas are golden brown and flaky.
