Demi-glace warm. At this point, the espagnole is prepared, and when it is finished, the brown stock is added in equal portions to the espagnole. Demi-glace keeps very well, about six months refrigerated or almost indefinitely frozen. Due to the considerable effort involved in making the traditional demi-glace, chefs commonly substitute a simple "jus lié" of veal stock or to create a simulated version, which the American cookbook author Julia Child referred to as a "semi-demi-glace"(i.e. sans espagnole sauce). However, even today, many chefs who prepare French "haute cuisine" use a demi-glace prepared in their own kitchen. Concentrates and mixes, mostly
French cuisine contrôlée" (AOC) (regulated appellation) laws. French cuisine was made important in the 20th century by Auguste Escoffier to become the modern haute cuisine; Escoffier, however, left out much of the local culinary character to be found in the regions of France and was considered difficult to execute by home cooks. Gastro-tourism and the "Guide Michelin" helped to acquaint people with the rich bourgeois and peasant cuisine of the French countryside starting in the 20th century. Gascon cuisine has also had great influence over the cuisine in the southwest of France. Many dishes that were once regional have proliferated in variations