Instructions

1. Make the filling:
2. Heat the oil in a medium skillet over medium heat until shimmering. Add the shallot and jalapeños and cook, stirring occasionally, until the shallot begins to brown, about 5 minutes. Add the garlic powder, black pepper, coriander, turmeric, and salt and continue to cook, stirring, for 1 minute.
3. Add the sirloin and peas and cook, stirring often, until the beef is cooked and most of the juices have evaporated, about 8 minutes. Stir in the cilantro and remove from heat. Set aside to cool completely.
4. Fill and bake the samosas:
5. Arrange a rack in the middle of the oven and heat to 400°F. Line a large baking sheet with parchment paper and set aside.
6. In a small bowl, whisk the egg and milk together to make an egg wash and set aside.
7. Place the puff pastry on a cutting board. Cut out 6 (4 1/2- by 4 1/2-inch) squares of dough. Place about 1 1/2 heaping tablespoons of filling on the bottom half of each square of dough. Fold the dough over the filling, gently pressing out any air pockets, then crimp the edges closed with a fork. (Freeze any leftover filling in an airtight container for up to 1 month.)
8. Place the samosas 2 inches apart on the baking sheet. Brush each samosa with the egg wash.
9. Place the baking sheet in the freezer for a few minutes before baking to firm up the butter. The chilled butter will melt slowly, producing steam as the pockets bake, which makes a crisp, even pastry rather than a lopsided and mushy one.
10. Bake the samosas until puffed and brown, about 15 minutes.