To roast it, I slathered it with barbeque sauce, and put it in a slowish oven for slow cooking until the marrow was bubbling out and a lot of juices had come into the pan. Then I deglazed the pan with a large slug of merlot and some water. In the meantime, I'd lightly sauteed a very large onion chopped up in the 20 quart soup pot, and had chopped carrots, celery, and parsley. I put the hunk o' beef/bones and all its pan juices into the soup pot with the onions, added the carrots, celery, parsley, an unmeasured (but probably a heaping tablespoon or more) amount of whole black peppercorns, an entire head of garlic (the cloves peeled of course, but not further chopped), enough small bay leaves (last of a jar) to equate to maybe four larger ones, and a solid slug of Italian seasoning, and enough water to just cover the lump of meat/bone. Brought it up to a low boil, then down to a simmer and left it.
And left it. And left it. As the bones came apart from the ligaments, we pulled them out, along with anything that looked likely to be troublesome. And left it. On Friday, I added a large can of petite diced tomatoes and my husband couldn't wait any longer and had some that evening. By this time, even on simmer, it had cooked down to less than 10 quarts. I pulled out two quarts of just the broth for use as brown stock later, and froze those, then put the rest of the liquid in a smaller pot (now that it fit) and added back in the vegetables and meat and chilled again to get the rest of the excess fat off (much easier than skimming it while it's hot!) It was probably about 4 1/2 quarts at this point, not sure. Maybe even 5 or so, in an 8 quart pot.
When I heated that for supper last night, I added a can of black beans (drained), a can of Ro-Tel tomatoes and green chilis with cilantro and lime juice, 4 cups of water, some salt (no salt had been added until then) brought that to a boil, then added 3/4 cup of pearl barley, put the lid on, turned it down, and when the barley was done....wow. A seriously good hearty beef-based soup with a velvety feel to the liquid and a complex set of flavors with nothing sticking out too much. The beef bits (which cooked any other way would've been tough as boots) had softened but were not mushy. It's much the same process as I've used with other beef soup bones, but a markedly better soup, so I think it must be those massive bones with ample marrow in them..and maybe the extra day of simmering to really meld the flavors. Dunno, but I'm doing it again.
Today I've put a quart or two of the remaining final soup into containers for the freezer. We'll see how it tastes when defrosted. The rest is now in a smaller pot (more convenient) and probably won't last the day.