1 can (14.5 ounces) stewed tomatoes, drained and chopped
2 tablespoons chopped fresh jalapeno pepper
1 teaspoon ground cumin
1 cup chopped or shredded roast beef, firmly packed*(see Notes)
1 package (14.1 ounces) refrigerated piecrust dough
1/2 cup shredded Pepper Jack cheese
1 egg yoke
1 tablespoon water
Preheat oven to 400 degrees F.
In a 3-quart saucepan, combine tomatoes (drained), jalapeno, and cooked roast beef. Place over medium heat and bring to a simmer (or very low boil) to heat through. While meat mixture is heating, spray a baking sheet with nonstick cooking spray, set aside.
Roll piecrust out on a lightly floured surface. With a pizza cutter, cut each piecrust dough circle into quarters. In the center of each piece of dough, place 2 tablespoons of meat mixture and 1 tablespoon cheese. Fold dough corners into the round edge and pinch with your fingers to seal. Seal bottom of each empanada by pressing the tines of a fork along the edge. Transfer empanadas to prepared baking sheet. (Repeat with remaining dough quarters, beef and cheese.)
Mix together egg yolk and water. Brush lightly over tops of empanadas. Bake, uncovered, until tops are golden brown and crust is flaky, about 8 to 10 minutes. Remove from oven and cool slightly (about 5 minutes), and then serve.
You can use leftover roast beef or purchase the already prepared roast beef ( in au jus) in the refrigerator section of your grocery store. Be sure to drain any natural or added juices from the meat before measuring.