In a large skillet, heat the olive oil over medium heat. Add the chopped onion and minced garlic, sauté for about 3-4 minutes until softened.
Add the ground beef or chicken to the skillet, breaking it up with a spatula. Cook until browned and no longer pink, about 5-7 minutes.
Stir in the chili powder, cumin, paprika, salt, and pepper. Cook for an additional 2 minutes until the spices are well combined and fragrant.
While the meat is cooking, heat the corn tortillas in a separate pan over medium heat for about 30 seconds on each side until warm and pliable.
To assemble the tacos, place a generous spoonful of the meat mixture on each tortilla. Top with chopped cilantro, diced tomatoes, avocado slices, and crumbled queso fresco.
Serve the tacos immediately with lime wedges on the side for squeezing over the top.