01 - Carefully wash collard greens, remove stems, and slice leaves into bite-sized pieces.
02 - Add collard greens, smoked ham hock, onion, and garlic to a large stockpot along with water.
03 - Bring mixture to a boil over high heat. Reduce heat to low, cover, and simmer for 1 hour.
04 - Stir in apple cider vinegar, kosher salt, black pepper, and crushed red pepper flakes. Cook uncovered for 45 minutes, stirring occasionally until greens are tender.
05 - Remove ham hock, shred meat, and return to pot. Stir well and serve hot, with reserved broth.