Preheat your oven to 375°F (190°C).

Peel and slice the potatoes. Toss them with olive oil, salt, black pepper, and 1/2 tsp sweet pepper. Arrange them in a baking dish.

Bake the potatoes in the preheated oven for about 20 minutes, or until they start to become tender.

While the potatoes are baking, heat a skillet over medium heat. Add a bit of olive oil and cook the chopped onion until translucent.

Add the ground beef to the skillet, season with salt, black pepper, 1/2 tsp sweet peppers, and oregano. Cook until the beef is browned.

Stir in the crushed tomatoes and cook for another 5 minutes.

Pour the beef mixture over the potatoes in the baking dish. If using, sprinkle mozzarella on top.

Return the dish to the oven and bake for an additional 20 minutes, or until the cheese is melted and bubbly.

In a large bowl, whisk together the lemon juice, sea salt, black pepper, and extra virgin olive oil.

Thinly slice the fennel bulb using a mandolin. Slice the apple and celery stalks.

Add the fennel, apple, celery, fennel fronds or parsley, and toasted walnuts to the bowl. Toss everything together to coat with the dressing.

Top with grated Parmesan cheese.