Mix together the ground beef, oregano, tomato sauce, garlic, and salt and pepper. Form into meatballs. Stuff those meatballs with a small amount of the cheese and then reform so cheese is on the inside.

Heat olive oil in a skillet over medium heat and then pan-fry the meatballs for 5-6 minutes or until browned on all sides and cooked through. Let stand for a few minutes before serving.