Except for white soups, to which arrow-root is, we think, more appropriate, we prefer, to all other ingredients generally used for this purpose, the finest and freshest rice-flour, which after being passed through a lawn-sieve, should be thoroughly blended with the salt, pounded spices, catsup, or wine, required to finish the flavouring of the soup. Sufficient liquid should be added to it very gradually to render it of the consistency of batter, and it should also be perfectly smooth; to keep it so, it should be moistened sparingly at first, and beaten with the back of a spoon until every lump has disappeared. The soup should boil quickly when the thickening is stirred into it, and be simmered for ten minutes afterwards. From an ounce and a half to two ounces of rice-flour will thicken sufficiently a quart of soup.
Instead of this, arrow-root or the condiment known by the name of tons les mois, which greatly resembles it, or potato-flour, or the French thickening called roux (see page 92) may be used in the following proportions: - Two and a half ounces of either of the first three, to four pints and a half of soup; to be mixed gradually with a little cold stock or water, stirred into the boiling soup, and simmered for a minute.
Six ounces of flour with seven of butter,* will be required to thicken a tureen of soup; as much as half a pound is sometimes used; these must be added by degrees and carefully stirred round in the soup until smoothly blended with it, or they will remain in lumps.
All the ingredients used for soups should be fresh, and of good quality, particularly Italian pastes of every kind (maccaroni, vermicelli, etc.), as they contract, by long keeping, a peculiarly unpleasant, musty, flavour.
* We would recommend any other thickening in preference to this unwholesome mixture.
Onions, freed from the outer skin, dried gradually to a deep brown, in a slow oven, and flattened, will keep for almost any length of time, and are extremely useful for heightening the colour and flavour of broths and gravies.*