Croquettes may be made from almost any food material. The crisp, brown outside is attained by rolling in egg and crumbs and frying in deep fat. That process is common to all croquettes, and all varieties may be grouped under two heads, those having a basis of white sauce, and those which have not. Some are made of meat and fish cooked tender, minced fine, while the sauce is double the usual thickness, and egg is sometimes added to these.

Others are made of vegetables, and egg alone is generally used to hold them in shape. These two classes may unite in one, as in fish balls where sometimes creamed salt fish is combined with potato and egg, or in macaroni croquettes.

The difficulty some cooks experience in making croquettes is due chiefly to the variability of materials, especially in the amount of moisture. It is practically impossible to cover this by any recipe. The way meat or vegetables are cooked, drained, and chopped or mashed makes a difference in the amount of sauce needed to shape them into croquettes. The temperature at which the croquettes are handled is another important point.

The ideal croquette should be soft and creamy inside when served, and yet keep its shape, and be crisp and brown outside. It is not necessary to use one kind of meat, fish, or vegetable, often two or three are combined in one form. Chicken and veal, or either, or both, with brains, sweetbreads or mushrooms, or oysters are often found in one recipe.

Equal quantities of meat and sauce, or more of either one, may be used. When the meat or fish is moist (canned salmon, for example), the sauce should be a trifle thicker than when baked fish or roast chicken is used. When the meat is chopped fine, more sauce may be used than if it were cut in small cubes. A meat chopper shortens the preparation. Meat becomes pasty when chopped while hot.

So much depends upon the seasoning already given the meat that no recipe can be followed implicitly. Frequent tasting should be the rule. Celery salt goes well with veal and chicken; lemon juice with fish; mustard with ham and sometimes with fish; cheese with macaroni and rice. A suspicion of onion with almost everything. Tasteless meat, even that from which bouillon has been made, can be transformed into savory croquettes with a tomato sauce and a flavor of onion. Though the flavor had been taken for the soup, much of the nutriment remains in the meat.

After meat, sauce, and seasoning are thoroughly mixed, the whole is to be spread in shallow pans to cool. These pans or plates should be greased or lightly sprinkled with fine crumbs. A piece of paraffin paper placed on top the mixture while it is cooling prevents the formation of a skin-like crust. This mixture should be thoroughly chilled; it may be made one day and fried the next.

For the second class of croquettes, including all such as potato, parsnips, beans, chestnuts, etc., the cooked vegetable is mashed, seasoned, and with it is mixed beaten egg, or the yolk only. These croquettes are usually shaped while warm, since they hold together better, and are less liable to crack while frying.