Preheat the grill for high heat.
In a medium bowl, mix together corn, red onion, jicama, red bell pepper, and cilantro. Stir in lime juice and zest.
In a small bowl, combine cayenne pepper, ground black pepper, and salt. Brush each fillet with olive oil, and sprinkle with spices.
Place fillets on grill, and cook for 3 minutes per side. For each taco, top two corn tortillas with fish, sour cream, and corn salsa.