Before I use Tuscan kale, I like to remove the thick stems. I've seen home cooks do this with a knife, which you can do if you fancy. I have a quicker way. Working one leaf at a time, firmly grab the end of the stem with one hand. With the other, use your thumb and index finger to firmly pinch together the bottom of the leaf on either side of the stem and pull away from the stem end, stripping off the leaves in one go.