Many people don't really know what it means to parboil something. When you make parboiled kale, it simply requires cooking in boiling water first before continuing the process with another cooking method, such as sauteeing.
You can use the stalks or not. But if you DO, then you can just leave them attached to the kale.
Boil a pot of water.Add the kale and cook for just a few minutes, until the colors are vibrant. Carefully remove from the water and drain completely.
Your kale is now parboiled and can be used in any way you'd like.
This technique is a wonderful way to keep the colors bright if presentation is important. Another reason to parboil your kale first is if you're preparing a stir-fry -- you can parboil all the veggies first so they finish stir frying at the same time. Or you can saute the kale in a bit of extra-virgin olive oil until tender.