Sauce brune is one of the basic French sauces (gravies). It's closely related to sauce espagnole and sauce demi-glace. In the past I've been using an English recipe for sauce demi-glace, from “Penguin Cordon Bleu Cookery” by Rosemary Hume and Muriel Downes, in fact quite reputed cooks, but their recipe is subtitled “brown sauce” (i.e. sauce brune) and by comparison with the French recipes it looks rather primitive.

The following recipe comes from “La cuisine de Madame Saint-Ange”, who spends two and a half pages describing in minute detail all the points to pay attention to. Unlike the British recipes, the French include meat.

Ingredients

Quantities for one litre of finished sauce:

quantity		ingredient		step
80-100 g		butter		1
100 g carrots				1
100 g		onion		1
100 g		lean belly pork (“lard maigre”)		1
4-5 stems		parsley, without leaves		1
2 stems		thyme		1
1		small bay leaf		1
50-60 g		flour		2
300 ml		good white wine		3
1.5 l		stock		3
40 g		tomato paste		3
50 g		mushroom peelings		4
40 ml		madeira wine		9

Preparation

1. Finely chop the carrots, onion, pork and add the herbs (the result is called mirepoix) and fry in the butter over low heat until they start to brown, about 10 minutes.
2. Stir in the flour and brown gently over a period of 12 to 15 minutes. The flour shouldn't get too brown. Stir frequently to avoid any excessive browning.
3. Reserve 200 ml of the stock for later. Gradually add the rest, along with the wine, to the flour and mirepoix mixture, stirring to mix in the flour. Add the tomato paste.
4. Bring to the boil and add the mushroom peelings.
5. Lower the heat and boil gently in an open pot for an hour, removing the scum the forms from time to time.
6. Pass the sauce through a sieve into another pot, pressing out the juice from the mirepoix. Bring to the boil and again cook over a very low heat, so that the sauce boils only in one corner of the pot. Continue to remove the scum, adding the reserved broth in small portions from time to time.
7. After about half an hour, the sauce is effectively finished. Madam Saint-Ange writes:

   When the dépouillement is finished, the sauce must not show an atom of fat. And all the heavy and cloying parts of the flour will have been eliminated, and what remains communicates a light syrupy consistence to the sauce.

8. If more than a litre of sauce remains, reduce to a litre.
9. Add the madeira. At this point, Madame Saint-Ange wants the sauce passed through another sieve. I can't see what good this does, since there are no lumps in it.