Prep the Brussels sprouts: Cut off the woody ends and remove any damaged outer leaves. Rinse and dry well, then slice very thinly with a sharp knife, mandoline, or food processor.
Add the mix-ins: Transfer the shaved Brussels sprouts to a large bowl. Add the dried cranberries and roughly chopped walnuts.
Make the dressing: In a small bowl, whisk together 4 tablespoons extra virgin olive oil, 2 tablespoons lemon juice, 1 tablespoon honey, 1 tablespoon Dijon mustard, 1 teaspoon salt, and ¼ teaspoon black pepper until smooth and well combined.
Toss and serve: Pour the dressing over the salad and toss well until everything is evenly coated. Serve right away, or let it sit for 10 to 20 minutes for slightly softer Brussels sprouts.