We may here mention, before leaving the subject of ingredients, that leeks and garlic are a substitute for onion, and can also be used in conjunction with it.
As a rule, in vegetarian cookery clear soups are rare, and, of course, from an economical point of view, they are not to be compared with thick soups.
Some persons, in making stock, recommend what is termed bran tea.

Half a pint of bran is boiled in about three pints of water, and a certain amount of nutriment can be extracted from the bran, which also imparts colour.
For the purpose of colouring clear soups, however, there is nothing in the world to compare with what French cooks call _caramel_.

Caramel is really burnt sugar.

There is a considerable art in preparing it, as it is necessary that it should impart colour, and colour _only_.

When prepared in the rough-and-ready manner of burning sugar in a spoon, as is too often practised in English kitchens, this desideratum is never attained, as you are bound to impart sweetness in addition to a burnt flavour.