Preheat the oven to 150°C. Roughly chop the tomatoes and put in a pan with their juices. Add a little oil and the oregano, and season with salt and black pepper. Cook gently over a medium heat, stirring occasionally, until the tomatoes break up and reduce into a thick sauce and put to one side. Beat the eggs with salt and parmesan and make 8 small omelettes. Place four of the omelettes in an oven dish side by side, and cover each with a slice of ham and some provolone; cover each with another omelette and pour over the prepared tomato sauce. Bake them in the oven for a few minutes and then serve.