In a small bowl combine oil, 3 tablespoons of the lime juice, the cilantro, ancho chile pepper, and garlic. Place fish in a medium glass baking dish. Pour mixture over fish, turning to coat. Cover and chill for 15 to 20 minutes.
For slaw, in a medium bowl combine the remaining 2 tablespoons lime juice, the mayonnaise, cayenne pepper, and salt. Add mango, cabbage, jicama, and sweet pepper, turning to coat. Season to taste with additional cayenne pepper and salt.
Remove fish from the marinade (it should have some of the marinade still clinging to it). Discard remaining marinade. For a charcoal or gas grill, grease grill rack. Place fish on the rack of a covered grill directly over medium heat. Grill for 8 minutes or until fish flakes easily when tested with a fork, turning once halfway through grilling. Transfer to a plate; keep warm. Grill tortillas about 40 seconds or until heated through, turning once halfway through grilling.
Break fish into 2-inch chunks. Top each tortilla with some of the fish; top with slaw.