When ready to serve the salad, combine the spinach and arugula mixture in a large bowl. Add the shaved brussels sprouts, cooled sweet potatoes, farro, quinoa, apple slices, red onion and toasted pumpkin seeds.
Drizzle the top with some well whisked vinaigrette, to taste; toss to coat evenly. Serve immediately with freshly cracked black pepper on top. Enjoy.