Veal stock is a mildly flavored, but very rich, liquid used as the base for many types of sauces, especially in French cuisine. It is made by cooking veal bones in a large amount of water and reducing that water over time to extract the bones' flavor. Aromatic vegetables and herbs such as onions, celery, carrots, thyme and leeks can be used to enhance the overall flavor and round out the taste. There are two separate types of veal stock, the brown variety made from roasted bones, and the white type that is nearly identical except the bones are not roasted first. Once the stock is complete, it can be further reduced into a thick glaze known as a demi-glace or into an almost syrupy state known as a glace de viande.
One of the reasons why veal stock is a treasured ingredient in many sauces and dishes is that, unlike beef stock, it has a muted meat flavor that does not usually overpower other ingredients. Another aspect of veal stock is the higher amount of collagen found in the bones and cartilage of the younger cattle. The collagen is extracted and held in the water of the stock, turning into a light gelatin that gives the liquid a rich and substantial texture in the mouth. The process of slowly extracting the collagen and other flavors in the veal bones can take more than a day in some cases, which has given veal stock a reputation of being difficult to prepare.
There are a number of ways to make veal stock, but the simplest is to boil the bones twice. This method involves first boiling the veal bones to cook them, and then placing the cooked bones into a new pot of water and reducing the liquid until a stock has formed. While simple, this method is not often used in high-end presentations because, the stock tends to be cloudy in appearance.
One of the most classic French ways of preparing veal stock begins by roasting the bones, along with any aromatics that are going to be used, in an oven until browned. The browned ingredients are then boiled in water until the stock comes together. After this first batch of liquid is strained and set aside, the bones are placed in a second pot of water and boiled down for hours, until a second, more lightly flavored stock known as a reimage is created. The final step is to combine the first and second liquids in a single pan and reduce them together into the final veal stock.