Score the inside (like you would an avocado), then remove a bit of the insides of the zucchini. Chop into small pieces and set aside. Brush the zucchini with 1 tablespoon of olive oil and sprinkle with salt and pepper. Arrange in a large 12x9" roasting dish and roast for 10 minutes.
Meanwhile, heat an additional tablespoon of oil in a medium skillet over medium heat. Add in onion and beef and sprinkle generously with salt and pepper. Cook for 2 minutes. Add the bell peppers and onions along with a pinch of salt and pepper. Add the tamari or coconut aminos and worcestershire sauce and allow to bubble and caramelize. Coat all the veggies and meat in the sauce.
Layer the roast beef and sauteed vegetables onto the zucchini and top with shredded cheese.
Return to the oven for 5 minutes until golden brown.
Garnish with parsley if desired and serve immediately.
Notes
To make this recipe gluten free we've used tamari and gluten free worcestershire sauce. You can also use coconut aminos or soy sauce (if you don't need to make this gluten free) in place of the tamari. Also, tamari and soy sauce tend to be high in sodium, so make sure to look for reduced-sodium options if they are available.We also recommend using meat that is cut thin. You can request your butcher to do this for you, or you can do this at home by placing the meat in the freezer for 30 mins, and using a very sharp knife to cut the meat against the grain.Be aware that zucchini also tends to be watery, so make sure you scoop out as much flesh as you can and don't skip roasting the zucchini first before adding the filling! This will help to release water so that you're not left with a mushy zucchini boat.