Cut a pattern of incisions across the top of the roast every couple of inches, each long and deep enough to hold a slice of salt pork. Combine half the garlic, 1 cup of the onion (mince this finely), and 1/2 teaspoon of the black pepper, and push this mixture into the slits you've made for the salt pork. Press salt pork into the beef and tie it securely, trying to make the shape of the roast as even as possible for even cooking.
In a pot broad and deep enough to hold the roast with room to spare for all the braising liquid, melt the lard over medium heat. Brown the roast well all around, keeping the salt pork inside. Add all remaining seasonings, carrots, celery, parsley and thyme to the pot, cooking until the onions are limp. Add wine and enough hot beef stock or water to nearly cover beef. Add bones. Cover pot and simmer 4 hours, until beef is very tender.
Remove beef from pot to another dish that will hold dripping juices. Raise heat under liquid and boil hard, uncovered, 45 minutes. While boiling down the gravy, baste the roast so it doesn't dry out.
Remove salt pork strips from beef and slice it as best you can (it will fall into chunks and shreds; the smaller you shred it, the more it'll be like the legendary "debris"), putting the pieces into a separate serving or storage dish. Strain the gravy, season it to taste with salt, freshly ground pepper and optionally a small pinch or two of cayenne and pour it over the beef. There should be about a quart of gravy. The resulting mixture should be sloppy, luscious and profoundly beefy.
Serve on fresh, crisp crusted New Orleans-style French bread -- average po-boy size is at least nine inches. Make sure the French bread (a good baguette will do) is not chewy. The bread must be crispy on the outside and light on the inside. Serve your roast beef po-boys dressed (with lettuce, tomatoes, pickles, etc.) or with nuttin' on it, but "mynez" (mayonnaise, that is) really is a must. I like mixing plenty of horseradish into my mayonnaise, by the way. Optionally, you could serve this as a plate lunch or dinner with vegetables and potatoes as well.