Corned beef and cabbage is one of my absolute favorite meals. What we think of as Irish fare, corned beef and cabbage is a special feast for some people who only cook it for a St Patrick's Day dinner, but both St. Paddy's Day celebrations and corned beef, are actually American inventions, and also known as the traditional New England Boiled Dinner. A corned beef -- and the correct term is indeed "corned beef", not "corn beef" -- requires moist cooking, so it's perfect for the pressure cooker.
A corned beef is beef that has been pickled or cured. The word "corn" comes from an Old English usage that refers to a process that dry-cured meat in the days before refrigeration by packing them in coarse salt pellets, or “corns” of salt. "Corn" describes the size and shape of the coarse rock salt that is traditionally used for brining because it resembled a kernel of grain. If you live in the UK, this would be a Corned Silverside or "salt beef".
The brisket can be the Flat or Plank Cut that is leaner and has the distinctive grain we see in the slices. The Point Cut is a rounder, thicker cut with more fat in it and may be a little more expensive. Either cut will shrink by about a third during cooking. Be sure to add additional quantities if you plan to have leftover corned beef to use in recipes like stovies, bully beef stew, Ruben sandwiches, or hash.
Cooked in a regular pot, a corned beef takes about 4 hours, but in the pressure cooker, the cooking time is cut down to only about 50 minutes. Corned beef can be cooked a day in advance, refrigerated, and reheated by steaming in the pressure cooker for about 6-8 minutes. A corned beef is usually boiled to draw out the salt and fat, you can use water, but I like Guinness stout to add flavor... and because it sure goes good with a big corned beef sandwich the next day.
You can stretch your food dollar by buying a smaller corned beef and adding a wider assortment of root vegetables such as rutabagas, turnips, parsnips, sweet potatoes and onions. You also switch from cabbage to kale or Brussels sprouts. The leftovers can be mixed and mashed for new dishes like Dutch Whip, or make Irish Potato Farl, Colcannon, Irish Champ, or Kale Colcannon.