Coat a large saute pan with olive oil and add the garlic cloves and crushed red pepper. Bring the pan to a medium heat and cook the garlic until it gets golden and very aromatic. Remove the garlic and discard.
Add the 2 types of kale and stir to coat with the oil. Season with salt and add the chicken stock. Cover and cook for 2 to 3 minutes.
Uncover and stir to be sure that the kale is cooked evenly. Let the liquid evaporate. Sprinkle with sherry vinegar. Taste to make sure that the kale is seasoned perfectly.