In a large bowl, whisk the mayonnaise, lime juice and zest, Serrano, chili powder and ½ tsp. salt.
Preheat the grill to medium high heat. Brush the corn with oil, and season with salt and pepper.
Place the corn on the grill and cook, turning occasionally to char all sides, 4-5 minutes.
Remove from grill and after coolining for a few minutes, cut the corn from cob. Place the corn into large bowl containing dressing. Fold in bell pepper and diced mango.
Top with mango, cheese and cilantro. Salt and pepper to taste. Serve at room temperature or chilled with chips or crackers.