In a bowl, mix the olive oil, chili powder, smoked paprika, cumin, garlic powder, salt, and pepper. Add the chicken breasts and coat evenly with the marinade. Let it sit for at least 20 minutes to soak up the flavors.
Heat a grill or skillet over medium-high heat. Cook the marinated chicken for about 6-7 minutes on each side, or until fully cooked and golden brown. Remove from heat and let it rest for a few minutes before slicing it into strips.
While the chicken is resting, warm the tortillas in a dry skillet or on the grill for about 30 seconds on each side until soft and pliable.
On each tortilla, layer slices of the grilled chicken, diced mango, chopped red onion, and cilantro. If desired, add sliced jalapeño for an extra kick.
Squeeze fresh lime juice over the assembled tacos for a zesty finish.