Heat the olive oil in a large skillet over medium heat. Add the chopped onion and cook, stirring occasionally, until translucent, about 3-4 minutes.
Add the minced garlic and cook for an additional minute, stirring constantly to prevent burning.
Increase the heat to medium-high and add the ground beef to the skillet. Cook, breaking it apart with a spatula, until it's well browned and cooked through, about 5-7 minutes.
Drain excess fat if necessary, then stir in the chili powder, cumin, paprika, salt, and pepper. Combine thoroughly and cook for another 2 minutes to let the spices meld.
While the beef is cooking, prepare your toppings: shred lettuce, dice tomatoes, and set up the cheese and sour cream.
Warm the taco shells or tortillas as per the package instructions.
Assemble the tacos by layering the beef mixture into each shell, then top with lettuce, tomatoes, shredded cheese, and a dollop of sour cream.
Serve immediately and enjoy!