Unwrap the pie crusts and using a cookie cutter or bottom of a cup, cut out 3" circles.
Re-roll the excess pie crusts and cut some more. You should get about 50ish circles.
Put the circles on a plate and put them back in the fridge while you prepare the filling.
In a small pot with water, cook your potatoes until just tender. You don't want them to fall apart while mixing them later. Drain them and set aside.
In a large skillet, saute the onions and 1 tbsp. of curry powder until the onions start to sweat.
Add in the beef, soy sauce, salt, and remaining 3 tbsp. of curry powder. Cook until beef is browned. Add in your drained potatoes and mix well until all is combined.
Take off the heat and preheat your oven to 450 °F (232 °C)
Lightly spray 2 cookie sheets with some cooking spray.
Take your circles out of the fridge and start assembling your pockets.
Put about a tbsp. of filling in the center of the circle.
Fold in half to seal it, but don't pinch them shut yet. To seal the pockets, starting on one end, pinch and 'tuck', pinch and 'tuck', repeat until you get to the other end and reshape if needed.
Place them on the greased cookie sheet and take your beaten egg yolk and a pastry brush and brush the tops of the pockets with the yolk.
Bake for about 12-15 minutes or until they're golden brown.
Let cool on the cookie sheet for 5 minutes then transfer them to a cooling rack.
Notes
Source: The Cooking of JoyTo Store and Reheat: If you have leftover curry pockets, you can place them in an airtight container in the refrigerator and store them for up to 5 days. Reheat them in a 350ºF oven or your toaster oven; you can use the microwave too, but the crust won’t be as flaky that way.