Cut the broccoli florets into bite-sized pieces, and place them in a large mixing bowl. Add in the red onion and cranberries.
In a small bowl, combine the tahini, vinegar, maple syrup, salt, garlic, and several grinds of black pepper, and stir well to combine. Add 1 to 2 tablespoons of water, as needed to thin out the dressing. You want it to be thick, but pourable, to coat the broccoli. Taste the dressing and adjust any seasoning to taste. Keep in mind that the flavor will be diluted once it is poured over a pound of vegetables.
Pour the dressing over the broccoli, onions, and cranberries, and toss well to coat. Cover and let the salad marinate in the fridge for at least an hour. Just before serving, stir in the sunflower seeds to retain their crunch.
Leftovers can be stored in an airtight container in the fridge for up to 3 days.