Preheat oven to 325 degrees.

Cut the bacon or pork into 1 × ¼-inch sticks; these are called lardons.

Brown the lardons lightly in a frying pan with a little oil, to render out the fat.

Pour the rendered fat into a large skillet, adding a little oil if necessary, to film pan by 1/16 inch.

Set over moderately high heat. When almost smoking, brown the beef, a few pieces at a time.

Place the beef, as it is browned, in casserole or baking dish.

Pour browning fat out of skillet, pour in the red wine and scrape up into it all the flavorful brown bits.

Pour wine into casserole. Add the browned lardons to the casserole, and enough beef bouillon almost to cover the meat.

Stir in the rest of the ingredients and bring casserole to simmer on top of the stove.

Cover the casserole and set in lower third of oven. Regulate heat so liquid simmers slowly for 2½ to 3 hours, or longer, until beef is tender when pierced with a fork.

While the beef is simmering, prepare the onion and mushroom garniture.

Trim mushroom stems, drop mushrooms in a large basin of cold water, swish about for a moment, lift out into a colander, and dry on a towel.

Cut the caps into quarters, and the stems on the bias.

Heat oil and butter in a skillet until butter foam begins to subside, add the mushrooms, and toss over high heat for 3 or 4 minutes to brown the mushrooms very lightly.

Remove to a side dish until needed, then toss with the salt.

Drop the onions into boiling water, bring rapidly back to the boil for several seconds to loosen the skins.

Drain. Peel carefully so as not to disturb the onion layers.

Place in one layer in a heavy saucepan; add the butter and salt and enough water to come halfway up.

Cover and simmer very slowly for 20 to 30 minutes, or until onions are tender.

When the beef is done, set cover askew and drain the cooking liquid into a saucepan.

You should have about 2½ cups; if liquid has boiled down too much, add a little beef bouillon.

Skim off fat, bring liquid to the simmer, and taste very carefully for seasoning.

Cream the butter and flour in a small bowl with a rubber spatula, to make a smooth paste.

Pour in several spoonfuls of beef-cooking liquid and blend with a wire whip, then pour this mixture into the beef liquid.

Pour in the onion-cooking juices and bring liquid to the simmer, stirring.

Add the mushrooms and onions to the beef, pour on the sauce, cover and simmer slowly for 5 minutes to blend flavors.

Serve the boeuf bourguignon in its casserole, or arrange on a hot platter surrounded with boiled potatoes, noodles, or rice.