I think Brussels sprouts would go well with that. It's a favorite Italian vegetable, and earthy, like your main dish.
I like to boil the sprouts until just tender, then saute in a skillet (season with salt and pepper) with rendered bacon and a little minced garlic. Add a small hand of pine nuts or slivered almonds at the last.
Or you could just add them to the Osso Buco.
Don't forget some good crusty bread to mop up the tasty juices!
We get by with a little help from our friends