Preheat your oven to 400 F.
Scoop out the center of each zucchini half to create “boats” with a hollow center, but make sure to leave a thick rim.
4 zucchini
Brush the zucchini with olive oil and season with salt and pepper to taste.
1 tbsp. olive oil, Sea salt and freshly ground black pepper
Bake the zucchini in the preheated oven for 15 to 20 minutes.
Melt some cooking fat in a skillet placed over medium heat.
Cooking fat
Saute the onion and garlic for 2 to 3 minutes.
1 large yellow onion, 2 garlic cloves
Add the bell pepper and mushrooms, and cook until soft, about 5 minutes.
1 bell pepper, 6 oz. button mushrooms
Add in roast beef, season everything to taste, and cook for 2 to 3 minutes, stirring.
Sea salt and freshly ground black pepper, 1 lb thinly sliced roast beef
Fill each zucchini with the beef mixture and serve.