In a medium bowl, combine the mangos, bell pepper, onion, jalapeƱo, cilantro, and salt. Toss with the olive oil and fresh lime juice. Adjust the seasonings as needed. Cover and let stand at room temperature for at least 30 minutes.
In a small bowl, combine the cumin, onion powder, garlic powder, salt, and pepper. Rub the spice mixture onto the chicken thighs. Set them aside for at least 10 minutes to marinate.
Preheat a grill to medium direct heat. Grill the chicken for 6 to 8 minutes on each side, or until it is cooked through. Remove it from the grill, let it rest for 5 minutes, and slice it into strips.
Divide chicken between 8 tortillas and top each with salsa.