At least one practice lesson should be given on the making of these soups. The value of the vegetable water should be impressed upon the pupils, and it may be pointed out that these soups are an excellent way of using the cooking water and any left-over vegetable.
The difference between tomatoes and other vegetables should be noted. Tomatoes are a fruit and, as such, contain an acid. The acid would curdle milk and must be neutralized by the use of soda, before milk can be added.
Utensils used for cream soups
PRINCIPLES OF CREAM SOUPS
1. The liquid may be all milk, part vegetable water and milk, or all vegetable water.
2. The amount of flour used for thickening depends on the vegetable. Starchy vegetables need only 1/2 tbsp. to one cup of liquid; non-starchy vegetables need 1 tbsp. to a cup.
3. The ingredients are combined as follows:
(1) The liquid is heated and thickened with flour.