In large skillet over medium heat, sauté onions until soft and golden. Add garlic and jalapeño (if using) and cook for about a minute. Add ground beef and cook until browning. Spoon off fat if there is more than a spoonful or so.
Drain and rinse black beans. Reserve half the can for another use. Add beans to meat mixture along with salt and pepper. Heat through and set aside.
In second pan, sauté onion in butter until very soft and golden, adding garlic for the last minute. Stir in flour. Allow to cook for a minute, then add beef broth, tomato sauce and seasonings. Bring to a simmer, reduce heat and cook, stirring often until thickened, about 10 minutes.
Add ½ cup of prepared sauce to meat mixture and stir to combine.
Ladle about 1 cup of sauce into the bottom of a 9 x 13 baking dish.
Preheat oven to 350 degrees and ensure rack is set to middle of oven.
Divide filling into 8 equal parts. Lay in a line across tortilla and top with about 1 - 2 Tbsp shredded cheese. Roll tightly in a tube and place seem side down in baking dish over sauce. Repeat with remaining tortillas. If using corn tortillas, heat on both sides in a dry skillet to soften.
Pour remainder of sauce over top, spread to edges and sprinkle remainder of cheese over sauce.
Cover lightly with foil, avoiding touching the cheese and sauce, and bake for 20 minutes. Remove foil and continue to bake for 20-25 minutes until sauce is bubbling and cheese has melted.
Allow to rest at least 10 minutes before serving, garnishing as desired.