Cut the lid off the tomatoes, take out the meat with a spoon (can be kept in the refrigerator for other recipes). Moisten the outside of the tomatoes with oil and season the inside with salt, pepper and oregano.
Cut the ham into small pieces and fill equal parts with the tomatoes.
Beat a whole egg in each tomato and then sprinkle with parmesan.
Rub an ovenproof dish with oil, add the tomatoes and fry for 30 minutes. Finished.