Take one sourdough slice and spread over a thick layer of your lasagna mince mix.
Now sprinkle over parmesan cheese and oregano, then top with mozzarella and finally the other slice of bread.
Heat a frying pan and melt the butter until gently foaming. Add the sandwich and fry until golden on one side then turn over and cook until the cheese melts. Serve right away (not that you'd be waiting around to eat this bad boy).