Rinse greens several times to remove grit and drain.
Fold greens leaf in half and slice off the thick stem (discard stems); chop greens and set aside.
Heat oil in a large heavy pot and saute onions and thyme until onions soften, then stir in the greens, garlic, neck bones, broth, vinegar, hot sauce and seasonings to taste (add as much as you like- I don't mention salt because most broths and especially Cajun spices are really salty, but add some to taste if it is needed.)
Bring mixture to a boil, then cover, reduce heat to a simmer and cook for 40 minutes, stirring occasionally.
Add chopped potatoes to pot, cover again and simmer for 20-25 minutes more or until potatoes are fork tender.