It should be strained away when the required consistency is obtained, for if left in too long the flavour is apt to be found a little too strong for some tastes.
Sago, tapioca, rice, and semolina are all useful for thickening, and it is generally advisable to strain the sauces in which they are used, before sending to table.
If paste of flour and butter be used for thickening, there will be no necessity to use a strainer, unless the sauce becomes lumpy. This can generally be remedied, however, by prolonged stirring over the fire.
The paste is made by placing equal quantities of flour and butter on a plate, and working them together with a knife until the flour is thoroughly incorporated.
Use about one ounce each of flour and butter to one pint of sauce, or to two pints of soup.
For thickening dark sauces, stews, etc., flour which has been baked in the oven until it has turned a very light brown will be found better than white flour. If allowed to become too brown it will acquire a disagreeable flavour.
To procure fine bread crumbs, rub stale bread through a wire sieve. For this the hands should be scrupulously clean.
Should the crumbs be required coarse, rubbing the bread on a grater will answer the purpose.