In a large Sautee pan over medium heat begin cooking ground beef and onion together, crumbling meat into large pieces. Meanwhile drain and rinse black beans and corn in a large colander. When no pink remains in beef drain in colander over corn and beans. Leave set aside.

Return empty pan to heat. Add all ingredients for sauce. Stir to combine and bring to a simmer. Add colander contents to sauce. Stir to coat. Bring to a simmer for 10 minutes uncovered.

While sauce simmers, in a medium bowl mix all contents for masa dough until well combined. Note: You should have a firm yet moist dough that sticks together and could form a ball. If it's too dry add a little more water a tbs at a time. If it's too wet add a little more masa a tbs at a time.

Preheat oven to 400°F. Press a little less than 2/3 of the dough into the bottom and up the sides of a 2qt casserole dish. Fill with meat mixture.

Spread remaining masa dough over the top to cover. It actually works best to form chunks of dough into patties by hand and lay across the top evenly, then pinch seams closed.

Cover dish with foil. Place in oven and bake 50 minutes. Remove foil and bake an additional 10-15 minutes. When done, remove from oven and let cool about 10 minutes. Top with desired garnishes - cheese, sour cream, salsa, lettuce, etc - and enjoy!