Combine the cheese and butter in a mixing bowl and beat with a paddle attachment or just with a wooden spoon or spatula until well combined. Add flour, cornmeal and salt and mix well. Refrigerate while you make the filling.
Black bean Empanada filling:
Heat oil in a skillet over high heat and add onion. Cook, stirring for several minutes until onion is beginning to brown. Add jalapeño, garlic, tomato paste and spices and cook 60 seconds.
Add beans and mash up about half the beans with your spatula.
Add zest and turn off heat.
On a floured surface with a floured rolling pin, roll the dough out to ¼” thickness, or until it’s about a foot-and-a-half diameter circle. (If the dough doesn’t roll out easily — i.e. it springs back — let it rest longer)
Cut 6″ circles from it. (You should get about 8 circles.)
Plop 1/4 cup of filling onto the lower half of each circle and fold over to cover it.
Use a fork to mash the seam together.
Transfer to a baking sheet, leaving ½” between each.
(If you like, brush the tops with beaten egg for a glossy look.)
Bake at 375øF F for 15-20 minutes until golden brown.