This comes from Foodchannel.com, chef Michael Chiarello. The recipe calls for Cavolo Nero (Italian Black Cabbage,Toscano Kale), you can substitute with Swiss Chard,or Kale. .
The best time of year to buy toscano kale is after the first frost. If you see it in the supermarket, ask where it came from to ascertain if the kale has gone through a frost or not. Post-frost kale will be tastier than mature kale picked before a frost. The one exception to this is very young (small) leaves, which are naturally tender and good to eat raw, as in salads.
Nice way to use up a ham hock. I just watched him make this on tv today, and my goodnes did it look good