Beef and Caramelized Onion Empanadas

What do you do with leftover roast?  That is, if you are lucky enough to have leftovers...

Empanada Dough
3 cups flour
1 1/2 Tbsp. sugar
1/2 tbsp. salt
1/2 tsp. baking powder
1 egg
1 egg divided, yolk in dough recipe and white saved for sealing edges of empanadas
1/4 cup red wine vinegar
1/2 cup (1 stick) melted butter, cooled
1/2 cup plus 2 Tbsp. water
         Combine the flour, sugar, salt and baking powder in your mixing bowl.  In a small bowl whisk the egg, egg yolk and vinegar.  Add the egg mixture and the cooled butter to the flour and turn the mixer on low for one minute and blend together.  Turn the speed up to medium and add the water.  Mix for two minutes.  Turn the dough out onto a lightly floured surface and knead it just a couple of times.  Shape it into a disk, wrap in plastic and refrigerate at least 2-3 hours.

Saute some sliced onions in butter and EVOO until they are tender.

Roll out the empanada dough about 1/4 inch thick and cut 3 inch circles.
Spread a little grainy brown mustard on one side. Add the grilled onions and then some of the shredded beef.  Fold over and brush a little egg white around the edges, then seal them with a fork.  Bake on a cookie sheet lined with parchment paper in a 400 degree oven for 20 minutes.  They are delicious alone or even better served with queso blanco for dipping.