Preheat grill to medium-high.
Combine cumin, 1/4 teaspoon salt, black pepper, and paprika. Brush oil evenly over both sides of steak; rub spice rub evenly over both sides of steak.
Peel and wash corn. Smear corn in butter and mayonnaise, then sprinkle with chili powder. Wrap in aluminum foil.
Cut a piece of foil about 18 inches long. Coat foil with cooking spray, and carefully place directly on hot grill rack. Arrange steak on foil. Place wrapped corn on grill.
Grill 5 to 6 minutes in covered grill. Turn steak and corn over. Grill 5 to 6 minutes in covered grill or until steak reaches desired degree of doneness.
Remove corn once tender. Top corn with Cotija cheese, and a squeeze of fresh lime.
