Make poppy seed dressing: Combine all ingredients in a small bowl or jar. Whisk or shake vigorously until combined and creamy. Refrigerate if not using right away.
For the salad: Prepare greens. For the kale, remove leaves from stem. Discard stem (it's very bitter!). Chop kale leaves in to bite-sized pieces and scatter on a cutting board. Sprinkle with a little salt and rub/massage the kale for a minute or so, until it softens and darkens. Add kale to large bowl. For the Brussels sprouts, remove bottom 1/3 of sprout. Using a sharp knife, thinly slice sprout, turning it on to the flat side after a few slices and continuing to slice until it's all sliced. Add to the bowl with the kale. For the broccoli, remove several florets and finely chop both the flower ends and the stalk. Add to the bowl.
Add the dried cranberries and roasted sunflower seeds to the bowl. Dice apple (I don't peeand add to the bowl. Drizzle some of the salad dressing over the salad and toss. Add more dressing as needed.