Shave the Brussels sprouts: Trim the stem end and remove any yellowed or damaged outer leaves. Using a mandoline slicer or the slicing blade of a food processor, slice the Brussels sprouts as thinly as possible, about 2-3 mm thick. Transfer to a large bowl.
Make the vinaigrette: In a small bowl, whisk together the extra-virgin olive oil and fresh lemon juice until well combined. Season with salt and pepper to your taste. The dressing should be bright and balanced between acid and richness.
Combine and toss: Pour the vinaigrette over the shaved Brussels sprouts and toss gently to coat evenly. Let the salad sit for 2-3 minutes to allow the Brussels sprouts to soften slightly while remaining crisp.
Add the toppings: Sprinkle the toasted pine nuts, dried cranberries, and feta cheese crumbles over the salad. Toss once more to distribute all ingredients evenly, then taste and adjust seasoning as needed.