Using a mandolin, thinly slice brussel sprouts so they form a slaw-type looking consistency. Slice onions using mandolin as well.
In a bowl combine sprouts, celery, onion, cranberries, avocado, parmesan and toasted pine nuts. Toss to combine.
Meanwhile, whisk orange juice, lemon juice, lemon zest, dijon & shallot. Slowly pour in olive oil, whisking constantly to emulsify.
Season to taste with salt and pepper and whisk in xanthan gum if desired.
Pour vinaigrette over salad and toss to combine. Let sit for 10 minutes to break down the sprouts a bit.