1. To make the pastry, combine the flour, salt, baking powder, and curry powder in a large mixing bowl. Cut the butter into small pieces and add to the bowl. Working quickly and using your fingertips, squeeze together the flour mixture and butter and toss it together by scooping under the mixture with both hands. When the mixture resembles a very coarse meal, add the water to the bowl.

2. With floured hands, mix and squeeze the dough just until it forms a ball. Knead it once or twice to combine it fully (the less kneading, the better). Spread the dough into 2 pieces, flattening each into a thick pancake. Wrap in plastic and set them in the refrigerator to chill for at least 15 minutes. (The dough will keep in the refrigerator up to 5 days. Remove it from the refrigerator a few minutes before using it.)

3. For filling, mix together the beef, onion, scallions, garlic, peppers, and thyme in a large bowl. In a large skillet, heat the oil over high heat until it is very hot, and add the beef mixture. Fry until the meat is brown and the moisture is evaporated, about 8 minutes. Add the curry powder, salt, and black pepper, stirring occasionally over high heat, allowing a crust to form on the bottom of the pan.

4. Add the water and stir the mixture, scraping the bottom to incorporate the browned crust. Add the breadcrumbs and stir. The consistency should be like a thick stew. Add more water as needed. Cover, reduce the heat to very low, and cook for 15 minutes. Set it aside to cool.

5. Preheat the oven to 400 degrees. Cut each piece of the dough into 9 pieces. Using a rolling pin on a floured surface, roll out each piece of pastry into a rectangle shape with rounded edges. Spread a large spoonful of the cooled meat mixture over one side of the dough, leaving at least 1/2- to 3/4-inch border on the outside edge. Using your finger, paint water around the border. Fold the other side of the dough over, and roll and crimp the edges. Lightly press a floured fork around the edge of the patty.

6. Place the patty onto a cookie sheet and repeat the procedure with the remaining dough. The patties may be covered in plastic and frozen at this point for later use. Brush each patty with the egg wash and bake for 15 to 20 minutes, or until the patties begin to turn a golden color.