Cut the ends of the zucchini off, cut long wise in half and spoon out the insides, leaving a thin wall in each so that they can be stuffed with the filling. Mix the mint, pepper, oregano, water and mushroom soup together. Add the juice of the lemon. Take ½ of this mixture and add the hamburger, egg (beaten) and rice to it. Keep the other ½ for pouring over the stuffed zucchini. Stuff each zucchini with the mixture of hamburger, rice and the sauce. Put the zucchini in a casserole and spoon the sauce and left over hamburger filling over them.
Cover and bake at 350 degrees for one hour until cooked through.
Serve by slicing each zucchini into 2" pieces and covering with the sauce.
Sprinkle with parsley (optional).