Directions

• Heat oil in a medium skillet over medium-high until shimmering. Add mustard seeds; cover and cook until seeds start popping, about 30 seconds. Remove lid; add carrots, leek, and curry sprig; stir to combine. Stir in curry powder, garlic, crushed red pepper, salt, black pepper, and ginger. Reduce heat to medium-low; cook, stirring often, until carrots and leek are softened, about 3 minutes.
• Stir chicken and soy sauce into curry mixture; cook over medium-low, stirring occasionally, until chicken is cooked through, 6 to 8 minutes. Transfer to a bowl. Let cool 30 minutes. Discard curry sprig and any loose curry leaves.
• Preheat oven to 350°F with racks in upper third and lower third positions. Line 2 baking sheets with parchment paper; set aside. Working with 1 thawed roll at a time, use thumbs to flatten dough into a 3-inch-wide disk, creating a slight indentation in center. Spoon1 packed heaping tablespoon filling into center of disk. Fold disk in half to enclose filling. Pinch dough to seal, forming a purse shape. Bring 2 pointed ends together to meet in the middle on the seam side; press to seal and form a ball. Place filled ball on prepared baking sheet. Repeat with remaining rolls and filling, spacing 3 inches apart.
• Whisk together egg yolk and 2 tablespoons water. Brush dough balls lightly with egg wash. Bake in preheated oven until golden brown, 24 to 28 minutes, rotating pans halfway through bake time. Transfer rolls to a wire rack; let cool 10 minutes. Serve with tomato-chile sauce.