Slice the zucchini lengthwise and scoop out the pulp. Chop the pulp and set aside.
In a non-stick pan, brown the onion in the olive oil. Add the tofu or crumbled burger, chopped zucchini pulp, nutritional yeast, garlic salt and oregano.
Pour the tomato sauce into a 23 x 28 centimeter (9 x 11 inch) pan, place the zucchini "boats" in the sauce and fill the boats with the tofu/burger mixture. Cover with tin foil and bake for 30 minutes, remove the foil and bake 15 minutes more.
Serve boats on plates and pour over some of the sauce.