In a small bowl, mix together the paprika, garlic powder, onion powder, oregano, cayenne pepper, salt, and black pepper to create the blackening seasoning.
Pat the chicken breasts dry with paper towels. Rub the olive oil over the chicken, then generously coat both sides with the blackening seasoning.
Heat a large skillet over medium-high heat. Once hot, add the seasoned chicken breasts and cook for about 5-7 minutes on each side, or until the chicken is cooked through and has a nice char. The internal temperature should reach 165°F.
Remove the chicken from the skillet and let it rest for a few minutes before slicing it into strips.
While the chicken is resting, warm the tortillas in the same skillet for about 30 seconds on each side until they are soft and pliable.
To assemble the tacos, place a few strips of blackened chicken on each tortilla. Top with shredded lettuce, diced tomatoes, cheese, sour cream, and avocado slices. Garnish with fresh cilantro if desired.
Serve immediately with lime wedges on the side for squeezing over the tacos.