Warm the tortillas. Heat a dry skillet over medium heat.
Warm each tortilla for 30–45 seconds per side until soft and a little charred. Wrap in a clean towel to keep warm.
Sauté the aromatics. In a large skillet over medium heat, add olive oil (if using). Add the diced onion and cook 3–4 minutes until softened.
Stir in the garlic and cook 30 seconds until fragrant.
Brown the beef. Add the ground beef to the skillet. Break it up with a spoon and cook 5–7 minutes until browned. If there’s a lot of grease, drain excess fat, leaving about a tablespoon for flavor.
Add spices. Sprinkle in cumin, chili powder, smoked paprika, oregano, salt, and black pepper.
Stir well to coat the beef. Add 2 tablespoons water or broth to help the spices bloom and create a light sauce. Simmer 1–2 minutes.
Add lime and cilantro. Turn off the heat.
Stir in lime zest, lime juice, and chopped cilantro. Taste and adjust with more salt or lime if needed. The flavor should be bright and savory.
Assemble the tacos. Spoon the beef into warm tortillas.
Top with more cilantro, a squeeze of lime, and any of your favorite toppings.
Serve immediately. These are best hot, with extra lime wedges on the side.