Heat a 10 to 12- inch cast iron skillet over a medium-high flame until very hot. Add the oil, then the corn, garlic and onions, and allow to cook, unstirred for 1 to 2 minutes until just charred in spots. Remove to a bowl and allow to cool.
Add Hellmann's® or Best Foods® Mayonnaise Dressing with Olive Oil, clilantro, lime juice and zest, cumin, black beans and tuna and gently toss to mix well. Serve on a sandwich or on a bed of lettuce leaves with hot sauce and lime wedges to garnish.