Fill a large saucepan with salted water and bring it to a boil over high heat. Remove any loose outer leaves from the cabbage and set them aside. Place the whole cabbage head into the boiling water and blanch for 3 to 4 minutes, turning it if needed to ensure even cooking. This softens the leaves, making them easier to remove without tearing.
Carefully remove the cabbage from the water, keeping the water boiling. Let it cool for a minute or two until it's cool enough to handle. Gently pull the leaves off, cutting them at the base if necessary. If the inner leaves are still stiff, return the cabbage to the boiling water for another 3 to 4 minutes, repeating until all usable leaves are pliable and separated.