Heat olive oil in a large skillet over medium heat. Add diced onions and sauté until translucent, about 5 minutes. The onions should become soft and slightly golden, releasing a sweet aroma.

Add minced garlic to the skillet and cook for an additional 1-2 minutes until fragrant. Be careful not to let the garlic burn; it should turn a light golden color.

Stir in the drained black beans, ground cumin, chili powder, and salt. Cook for 5-7 minutes, allowing the beans to heat through and the spices to meld. The mixture should be thick and slightly creamy.

Preheat your oven to 350°F (175°C). Arrange corn tortillas on a baking sheet and warm in the oven for about 5 minutes. This will make them pliable and prevent cracking when filled.

Fill each warm tortilla with a generous spoonful of the black bean mixture. The filling should be evenly distributed to ensure each taco has a balanced flavor.

Squeeze lime juice over the filled tacos to add a burst of acidity that brightens the flavors. Serve immediately for the best texture and taste.

Optional: Top tacos with your choice of toppings like shredded lettuce, diced tomatoes, or avocado slices for added freshness and texture contrast.

Serve the tacos while the shells are still warm and crisp, enjoying the combination of creamy filling and crunchy shell. Adjust seasoning to taste.