Start by preheating a large stock pot over medium high heat.
Add olive oil and the diced red onions and soften for about 6 minutes, stirring occasionally.
Add apple cider vinegar, chicken stock, salt, cayenne pepper, garlic powder and Worcestershire sauce and bring to a simmer.
Add turkey leg and adjust salt to taste. (You can let this simmer without the greens for up to an hour for more smoky stock flavor if you have time)
Finally add the chopped greens into the pot over a simmer and stir to mix. Cover and let sit for about one hour or until the greens are soft to taste. Take care to not let the stock come to a boil, keep the simmer as low heat as possible.
Serve in your favorite bowl and add some of the turkey from the leg in your dish.