In a bowl whisk together grape-seed oil, miso, sesame oil, soy sauce, rice vinegar & garlic. Add creme fraîche, whisk to combine.
Use a mandolin or chef knife to shred Brussels sprouts, discarding the ends. Use your hands to separate.
Add Brussels sprouts to a large mixing bowl, add dressing & toss to combine.
Add pickled onions and cashews and toss once more. Serve immediately.