For the salad: Preheat a gas or charcoal grill. Peel back the corn husks. Remove the silks and replace the husks. Soak the corn in cold water for 30 minutes. Drain and place on the grill for 10 to 15 minutes. Cool completely and remove the husks. Using a sharp knife, remove the corn kernels. In a medium bowl, mix together the grilled corn, black beans, garbanzo beans, bell pepper, and mango.
For the vinaigrette: In a small bowl, combine the lime zest, lime juice, balsamic vinegar, basil, and cumin. Slowly add the oil, whisking constantly until the mixture thickens. Season with salt and pepper, to taste.
Pour the vinaigrette over the salad and toss well. Refrigerate for 1 hour, and toss again, before serving.