This is an heirloom Italian variety of kale called 'Lacinato'
My favorite way to eat kale is by roasting in the oven until it gets crispy. The texture is unbelievable. I don't know how to describe it other than airy and crispy. Better than popcorn.
Preheat oven to 375 (set to convection if you can).
De-vein kale and rip into bite sized pieces.
Toss with a drizzle of olive oil and a sprinkling of sea salt.
Let roast until crispy (about 10 minutes, unless you have other things in the oven, in which case it will likely take longer due to steam).