It is advisable during despumation to change saucepans twice or even three times, straining every time, and adding a quart of brown stock to replace what has evaporated. At length, when the sauce begins to get lighter, and about two hours before finally straining it, two lbs. of fresh tomatoes, roughly cut up, should be added, or an equivalent quantity of tomato purée, and about one lb. of Mirepoix, prepared according to Formula No. [228]. The sauce is then reduced so as to measure four quarts when strained, after which it is poured into a wide tureen, and must be kept in motion until quite cool lest a skin should form on its surface.
The time required for the despumation of an Espagnole varies according to the quality of the stock and roux. We saw above that one hour sufficed for a concentrated stock and starch roux, in which case the [Mirepoix] and the tomato are inserted from the first. But much more time is required if one is dealing with a roux whose base is flour. In the latter case six hours [19] ]should be allowed, provided one have excellent stock and well-made roux. More often than not this work is done in two stages, thus: after having despumated the Espagnole for six or eight hours the first day, it is put on the fire the next day with half its volume of stock, and it is left to despumate a few hours more before it is finally strained.
Summing up my opinion on this subject, I can only give my colleagues the following advice, based upon long experience:—
1. Only use strong, clear stock with a decided taste.
2. Be scrupulously careful of the roux, however it may be made. By following these two rules, a clear, brilliant, and consistent Espagnole will always be obtained in a fairly short time.
[23—HALF GLAZE]
This is the Espagnole sauce, having reached the limit of perfection by final despumation. It is obtained by reducing one quart of Espagnole and one quart of first-class brown stock until its volume is reduced to nine-tenths of a quart. It is then strained into a [bain-marie] of convenient dimensions, and it is finished, away from the fire, with one-tenth of a quart of excellent sherry. Cover the [bain-marie], or slightly butter the top to avoid the formation of a skin. This sauce is the base of all the smaller brown sauces.
[24—LENTEN ESPAGNOLE]
Practical men are not agreed as to the need of Lenten Espagnole. The ordinary Espagnole being really a neutral sauce in flavour, it is quite simple to give it the necessary flavour by the addition of the required quantity of fish [fumet]. It is only, therefore, when one wishes to conform with the demands of a genuine Lent sauce that a fish Espagnole is needed. And, certainly in this case, nothing can take its place.
The preparation of this Espagnole does not differ from that of the ordinary kind, except that the bacon is replaced by mushroom parings in the [Mirepoix], and that the sauce must be despumated for only one hour.