Sierra Empanada

1. Put the quartered onion, tablespoon salt and 1/2 gallon water in a pot and bring to a boil. Add the chicken and simmer for 40 minutes. Remove the chicken and let cool, then shred.
2. Put 1/4 cup olive oil and the diced onions in a pan and cook at medium-high heat until onions are translucent, 10 to 15 minutes. Meanwhile, put the chipotle, garlic and remaining 1/4 cup olive oil in a blender; blend, making sure to leave some little chunks. Add the shredded chicken to the sauteed onions, then add the chipotle mixture and crushed tomatoes. Mix well, then add black pepper and remaining 3 1/2 teaspoons salt. Mix and add chives. Let cool completely.
3. Drop tablespoon-size portions of filling in the center of each dough disc and fold so that the empanadas look like half-moons. Make sure the edges are completely sealed to prevent the filling from coming out while baking.
4. Preheat the oven to 400 degrees F.
5. Place empanadas on a lightly oiled sheet pan; brush with egg yolk if using, Bake until dough is nicely browned, about 15 minutes.

Empanada Dough:

1. Making the dough can be done by hand but it is easier in a mixer with a dough attachment. Mix the flour and salt in a mixer until well combined, about 1 minute.
2. Add the butter and mix until blended, another 2 minutes.
3. Add the egg and 1/4 to 1/2 cup water, adding gradually, and continue mixing until slightly rough to the touch.
4. Make the dough into a ball and finish kneading by hand until soft and smooth. Wrap in plastic wrap and put in the fridge for at least 30 minutes or overnight.
5. Unwrap the dough and roll out with a rolling pin until thin, but not too thin, so it doesn't break when folding.
6. Create discs with a 5-inch cutter for large empanadas or a 3-inch cutter for small ones. If not using immediately, use wax or parchment paper to separate the stack and refrigerate or freeze to use later.