Wash and zest orange, and set zest aside. Juice orange. Place orange juice, vinegar, honey, onions, garlic, sesame oil, and soy sauce in blender and blend until smooth. If necessary, use a spatula to make sure honey is not stuck in bottom of blender. With blender running on low, slowly drizzle in oil in a small, steady stream, to emulsify. Add orange zest and pulse to combine. Place dressing in a lidded jar and add sesame seeds, shaking to combine. Refrigerate until ready to use.