In a medium bowl, combine olive oil, fresh lime juice, minced garlic, ground cumin, chili powder, smoked paprika, salt, and black pepper to create the marinade.
Place the chicken breasts in the marinade, ensuring they are fully coated. Cover and refrigerate for at least 15 minutes.
Preheat a grill or grill pan over medium-high heat.
Remove the chicken from the marinade and grill for 5-6 minutes on each side or until the internal temperature reaches 165°F (74°C) and the chicken is cooked through.
While the chicken is grilling, prepare the fresh salsa by combining diced tomatoes, chopped red onion, chopped cilantro, and finely chopped jalapeño pepper in a small bowl. Mix well and set aside.
Once the chicken is cooked, let it rest for 5 minutes, then slice it into thin strips.
Warm the corn tortillas on the grill for about 30 seconds on each side until pliable and slightly charred.
Assemble the tacos by placing sliced grilled chicken on each tortilla, topping with fresh salsa, avocado slices, and crumbled queso fresco.
Serve immediately with lime wedges on the side for squeezing over the tacos.