01 - Heat olive oil or bacon drippings in a large pot over medium heat. Add diced onion and cook 4-5 minutes until translucent, then stir in garlic and cook 1 minute until fragrant.
02 - Add smoked turkey leg or ham hock if using, then pour in chicken broth. Bring mixture to a gentle simmer over medium-high heat.
03 - Add chopped collard greens in batches, stirring until each batch wilts enough to fit into the pot. Continue until all greens are added.
04 - Stir in salt, black pepper, and red pepper flakes if using. Reduce heat to low, cover, and simmer for 1 hour, stirring occasionally, until greens are completely tender.
05 - Remove meat bones, shred any remaining meat, and return to pot. Stir in apple cider vinegar, adjust seasoning to taste, and serve warm.