Begin by removing the fronds from a firm, smooth fennel bulb. Using a sharp knife or mandoline, slice the bulb and stalks thinly, aiming for pieces that are about 1/8 inch thick. Transfer the sliced fennel to a large mixing bowl.

Next, take 1 to 2 apples of your choice and wash them thoroughly. Core the apples, then slice them into thin, bite-sized wedges. Add the apple slices to the bowl with the fennel.

Gently add about 2 cups of fresh arugula to the bowl containing the sliced fennel and apples. Toss lightly to mix without bruising the greens.

Sprinkle a handful of crunchy walnuts and about 1-2 ounces of Parmesan cheese over the salad. Distribute these toppings evenly.

In a small bowl, whisk together 1/4 cup of olive oil, freshly squeezed lemon juice, and a pinch of salt and pepper. Mix until well combined.

Drizzle the dressing over the salad mixture, then toss gently to ensure everything is lightly coated.

Garnish the salad with reserved fennel fronds and serve immediately on chilled plates.