These are Escoffier's measurements. I would quarter them all except for the salt pork, carrot, onion, and thyme, oh yes, the wine also. I would also add a couple oz of diced celery if I had it around. Some cooks add other ingredients, such as turnips (!) for a peppery taste, calves' feet for a more unctuous texture, etc.

Make a brown roux out of the butter and flour, making sure that it does not burn at all. Keep it warm.

Bring 9 qt of stock to the boil; add the roux, and return to the boil, stirring well. Reduce the heat and let this simmer.

Fry out the fat of the diced salt pork, and in this fat add the carrot, onion, thyme, and bay leaves. Fry the vegetables golden and drain off the fat (I use this then to cook more vegetables for something like spaghetti sauce). Add the vegetables to the sauce in the pot. Deglaze the pan with the wine, and reduce the volume to half. Add this also to the sauce pot (M's note: the reduction is I believe unnecessary here).

Strain the sauce using a food mill or a tamis (M used to use a blender). Put the strained sauce into a clean pan and add 2 more qt of stock. Bring this to the boil and let simmer on low for 2 more hr. Strain it again and let it cool, stirring it occasionally. If the weather is cool, you can leave this out overnight; otherwise refrigerate it.

Next day, take the tomato puree and spread it thin over a nonreactive oven dish; cook it over low heat until it browns a little.

Bring the sauce to the boil; add the final 2 qt of stock and the tomato stuff. Bring the sauce to the boil one final time and simmer on low 1 hr. Skim off any scum as it forms. Strain the sauce again and let it cool, stirring it occasionally. This sauce is generally not used by itself but as an ingredient in other sauces and dishes. Recipe posted by Michael Loo