Rinse and drain the black beans.
Heat olive oil in a skillet over medium heat.
Sauté the diced onion until translucent, about 5 minutes.
Add minced garlic, cumin, and chili powder; cook for another minute.
Stir in the black beans and season with salt and pepper.
Cook the mixture for about 5-7 minutes until heated through.
Warm the tortillas in a separate pan or microwave.
Assemble the tacos by spooning the black bean mixture onto each tortilla, and top with desired toppings.
Serve with lime wedges on the side for squeezing over the top.