01 - Heat the olive oil or bacon drippings in a large pot over medium heat. Add the diced onion and cook for 4 to 5 minutes until translucent.
02 - Stir in the garlic and cook for 1 additional minute until fragrant.
03 - Add the smoked turkey leg or ham hock if using, then pour in the chicken broth. Bring the mixture to a simmer.
04 - Gradually add the chopped collard greens, stirring in batches until they are wilted and fit into the pot.
05 - Stir in the salt, black pepper, and red pepper flakes if desired. Reduce heat to low, cover, and simmer for 1 hour, stirring occasionally, until the greens are tender.
06 - Remove and discard any bones from the smoked meat. Shred any remaining meat and return it to the pot. Stir in the apple cider vinegar.
07 - Taste and adjust seasoning as needed. Serve warm.