Using a ribbon spiralizer or vegetable peeler, slice the zucchini into thin ribbons. Lay them flat on a clean paper towel and sprinkle the salt. Toss using your hands to distribute the salt and let stand for 15 minutes.
Fold the towel and twist it over the sink to squeeze out all the excess water from the zucchini. Set aside. Preheat your oven to 350 F/180 C and lightly grease a medium casserole.
Slice the mushrooms and mince the garlic. Place a skillet over high heat and add the ghee. Once the skillet is hot, add the mushrooms and cook for 3-4 minutes until golden.
Drop the heat to medium and add the garlic. Cook for 30 seconds, stirring continuously. Add the coconut milk and stir.
Drain the tuna cans and add their contents to the skillet. Add the zucchini ribbons and black pepper. Stir, taste, and adjust seasoning if needed.
Transfer to the casserole dish and bake for 10 minutes. Let it cool for 10 minutes before serving. Garnish with chopped parsley and serve with lemon slices.