Preheat the oven to 400°F. Line a large rimmed baking sheet with parchment paper and place the onion quarters on top. Pour the oil onto the onions and use your hands to thoroughly coat them.
Sprinkle with sea salt and pepper and roast for 40 minutes or until the onions are tender and golden brown.
Meanwhile, combine the cabbage, cucumber, bell pepper, salad greens, sunflower seeds, and dried cherries in a large bowl.
In a small bowl, whisk the almond butter and orange juice. Add water, if needed, to create a dressing consistency. Drizzle over the salad mixture and toss to combine. Add the roasted onions and serve immediately.