Rub the corn with olive oil and season with a little salt and pepper. Set aside.
To make salsa, cut the corn off the cob and add to a medium bowl. Stir in red onion, cilantro, lime juice, cotija cheese, salt, and pepper. Season to taste and add a little more lime if desired. Add burgers to buns and top with lettuce, avocado, and corn salsa. Serve!