Preheat oven to 425 degrees F. In a large bowl combine the sweet potatoes, onion, oil, salt, and pepper; toss to coat. Divide mixture among two 15 x 10 x 1-inch baking pans. Roast on two separate racks, uncovered, for 15 minutes. Add broccoli to pans. Roast 10 minutes more or until vegetables are browned and tender.
Meanwhile, for dressing, in a small bowl whisk together water, almond butter, lemon juice, soy sauce, garlic, ginger, and crushed red pepper until smooth.
Transfer sweet potato mixture to a platter. Drizzle with dressing. Sprinkle with coconut and nuts.