Home › The Belgian Kitchen › Muslin Sauce
Muslin Sauce
Melt a piece of butter the size of an egg, sprinkle and stir in some flour, adding water if it becomes too thick. Keep stirring over the fire for five minutes, and, still stirring, add pepper and salt and the yolks of two eggs. You may add the yolks of three or four eggs if you wish for a rich sauce. The last item is the juice of a lemon to your taste. This is a very popular addition to meat.
A plain flour-and-butter sauce enriched with yolks at the end — essentially a lemon-sharpened velouté made with water rather than stock. The quantities are given by eye, so a little arithmetic helps.
- Butter the size of an eggRoughly 2 oz, or 4 tablespoons. Match it with about the same volume of flour, a scant 1/4 cup, for a roux that will carry a cup or so of liquid.
- The unstated liquidNo quantity is given for the water; work backwards from the consistency you want. About 1 cup to 4 tablespoons of roux gives a coating sauce, which is what "adding water if it becomes too thick" is driving at.
- Water or stockThe recipe calls for plain water. Since the sauce is meant for meat, the cooking liquid or a light stock in its place costs nothing and improves it considerably.
- The hinge: the yolks must not boilThe hinge: don't boil the yolks -- The recipe adds the yolks over the fire, but keep the sauce off the boil once they are in; the flour base gives some protection, yet hard heat will still curdle it. Pull the pan off the heat, whisk in the yolks, and if you want them properly set, hold the sauce at 160-170F while stirring -- no higher.
- Temper them firstBeat the yolks in a bowl with a ladleful of the hot sauce before adding them back to the pan. Dropped straight into a hot roux they will string.
- Five minutes of stirringThat is a working roux-and-liquid cook, enough to lose the raw flour taste. Keep it at a bare simmer and stir the corners of the pan; flour sauces catch quickly.
- Lemon last, off the heatAcid added to a hot yolk-thickened sauce encourages it to split. Add the juice at the end, taste as you go, and start with half a lemon.
- YieldFour tablespoons of butter and a cup of liquid make roughly 1 1/4 cups of sauce, enough for four to six servings. It does not reheat well — make it as the meat rests.
The Belgian Cook Book was assembled in 1915 from recipes contributed by Belgian refugees who had fled the German occupation, and its cooking is marked throughout by economy: water where stock might be, butter measured against an egg rather than weighed. The name here may be an English rendering of sauce mousseline, though that is only a guess, and the classic mousseline is in any case a hollandaise lightened with whipped cream rather than a yolk-enriched roux. What the recipe actually describes is closer to a sauce bâtarde or "bastard sauce", the thrifty French cousin of hollandaise: a flour base carrying the butter and yolks so that far less butter is needed and the sauce is much harder to break. It is offered as "a very popular addition to meat", a pale, sharp sauce rather than a dark gravy.