Heat 1 tablespoon oil in a large nonstick skillet over medium heat. Using 2 tablespoons of the corn mixture to make each fritter, drop 6 fritters into the pan and flatten into 2-inch disks. Cover and cook until browned on the bottom, 2 to 3 minutes. Carefully flip and continue cooking, covered and adjusting heat as needed, until browned on the second side, another 2 to 3 minutes. Transfer to a plate and cover to keep warm. Repeat 2 more times with the remaining mixture and oil.