Begin by thinly slicing the Brussels sprouts, ideally using a mandoline for precision. Transfer the sprouts into a medium-sized bowl. Add the olive oil, lemon juice, toasted pine nuts, dried cranberries, pecorino cheese (if using), and chopped chives. Season generously with sea salt and freshly ground black pepper.

Allow the salad to rest at room temperature for approximately 15 minutes, which will help the flavors meld. Taste and adjust the seasoning as needed, finishing with a drizzle of additional olive oil if desired.