In a small bowl, combine the ingredients for the taco seasoning, then set the seasoning aside (or use an envelope of store bought taco seasoning).Preheat oven to 400.
Dice the onion and mince the garlic.Add the onion, garlic, and cooking oil to a large skillet.
Saute the onion and garlic over medium heat until the onion is soft and translucent (about 5 minutes).
Add the ground beef and prepared taco seasoning and continue to saute until the beef is cooked through, another 5 minutes.
Arrange the taco shells incasserole dish so they are all standing upright.If you do not have a dish that fits snug enough to hold them upright, use balled aluminum foil to act as book ends to help hold the line of tacos upright.
Drain the can of black beans well, but do not rinse them.A little sauciness helps keep the beef mixture moist.(I rinsed and drained mine).
Stir the beans into the seasoned beef and allow them to heat through.
Fill the tacos with the beef and bean mixture.
Sprinkle the shredded cheese over top.
Bake the tacos in the preheated oven for 7 to 10 minutes, or until the cheese is melted and the taco shells are golden brown on the edges.
While the tacos are baking, dice the tomato, jalapeno, and roughly chop the cilantro leaves.
Sprinkle the diced tomato, jalapeno, and cilantro over the tacos, and add a dollop of sour cream just before serving.