Prepare the Beef Filling:

1. Cook Beef: Heat the vegetable oil in a large skillet over medium-high heat. Add the ground beef and cook, breaking it up with a spoon, until browned and fully cooked, about 5-7 minutes.
2. Add Vegetables: Add the chopped onion to the skillet and cook until softened, about 3-4 minutes. Stir in the minced garlic and cook for another minute.
3. Season and Simmer: Add chili powder, ground cumin, paprika, oregano, and cayenne pepper (if using). Stir well to coat the beef with the spices. Pour in the tomato sauce and beef broth, and bring to a simmer. Cook for 5-7 minutes, until the sauce thickens and the flavors meld. Season with salt and pepper to taste.

Prepare the Tortillas:

1. Warm Tortillas: Heat the tortillas according to package instructions or warm them in a dry skillet over medium heat until soft and pliable. For crispy tacos, preheat the oven to 375°F (190°C) and bake corn tortillas for about 8-10 minutes until crisp.

Assemble the Tacos:

1. Fill Tortillas: Spoon the beef filling into the tortillas.
2. Add Toppings: Top with shredded lettuce, diced tomatoes, shredded cheese, a dollop of sour cream, and chopped cilantro.
3. Serve: Garnish with lime wedges for added freshness.