We got one of those Roemertopf unglazed clay pots as a wedding present going on 31 years ago, probably haven't used it a dozen times... saw it in the back of the cabinet and thought well, let's try it.
Didn't make that exact recipe, just cut a bunch of shoulder meat up into maybe two-inch cubes and soaked them in vinegar water overnight... then put them in the clay pot with some onions, carrots, and potatoes like a regular pot roast, put some Dijon mustard and a little butter on top of the meat and baked it at 300 for four hours. Drained the juice out, added some more mustard and a little cornstarch and reduced it to a sauce, turned out real well.
