<human>:  How do you cook authentic Mexican tacos?
<bot>: 
1. Begin by heating a large skillet over medium-high heat and adding some oil.
2. Add one onion, chopped, and one pound of ground beef, and cook until the beef is cooked through.
3. Add one tablespoon of chili powder, one teaspoon of cumin, and one teaspoon of oregano and stir to combine.
4. Add a pinch of salt and pepper and stir in one cup of salsa.
5. Rinse and drain one can of black beans and add to skillet.
6. Cook until mixture is heated through.
7. Using a warm corn or flour tortilla, fill each with a generous scoop of the taco filling.
8. Top with grated cheese, lettuce, and any other toppings you desire.
9. Serve with lime wedges, guacamole, and sour cream to complete your authentic Mexican tacos.