This was dinner last night, moments before it was consumed. Donna said, "This is the best cabbage I've ever had," and, back at the stove, looking for thirds on the corned beef, "This is all you made?" All in all, a success. I've used this particular preparation several times and it can't be beat, a really smart strategy for cooking and serving and making use of all the flavors and juices and soft textures.
First cook your corned beef (simmered for a few hours, braised, wrapped in foil with sliced onions for 4 hours at 250—how I did it—or even cooked sous vide). Only way not to cook this is slow roasting (a perfectly fine strategy but won't give you the liquid you need to finish the cabbage here).
To complete the meal. Saute 4 or 5 ounces of bacon lardons. Poach red potatoes in hot but not boiling water till tender, about a half hour. Cut your cabbage into wedges, through the root so that the leaves stay attached. When the bacon is cooked and the fat is rendered, sear both sides of the cabbage wedges in bacon fat (never miss the chance to say "bacon fat," it always invites), then add enough of the beef liquid to the pan to come halfway up the cabbages, cover and simmer till the cabbage is tender, 10 minutes or so. Keep the beef covered or wrapped so it doesn't dry out. When the cabbage is tender, stir a tablespoon of Dijon mustard into the cooking liquid. Add the beef to the pan, cover and keep on low so that it all stays steaming hot. Drain the potatoes, slice them, toss them with butter and parsley and salt.
I sliced the beef right there in the pan, but you could remove it to a cutting board, slice and serve or slice and return it to the pan or to a platter. Just make sure it's in plenty of the hot cooking liquid. Serve the cabbage, corned beef and potatoes, spooning plentiful sauce over everything. A great even elegant way to serve this unbeatable fare.
3/19: Comment Call out, from "Jose Canseco": On another note, my 100 year old Irish grandmother-in-law says in her day they never ate corned beef, rather corned pork. Her preferred part of the hog for pickling is spare ribs, so now I throw a few racks into the brine along with the brisket and tongue I pickle every year and the result is fantastic.
Great idea, and thanks for historical note. This would work great. For those who want to try this, be forewarned that spare ribs cured with sodium nitrite will have take on a distinctly bacony flavor. I recommend searing on grill, then adding to the pot!