Heat oil in a skillet over medium heat. Add in beef and cook until browned and fully cooked, about 5-10 minutes. Remove beef from skillet and set aside.

Add onions and peppers to the skillet with any remaining beef juices and fry until vegetables are tender, about 10 minutes.

Drain any remaining liquid and add the beef back to the pan. Add the cheese and stir until cheese has melted throughout. Season with italian seasoning and salt/pepper to taste.

Scoop beef mixture into lettuce leaves and serve.