sharing knowledge 1

 "Demi-glace ,,,rich brown sauce, it is the most important sauce we need".Basically and traditionally  Demi-glace is the combining equal part of brown sauce and brown stock ( veal or chicken stock ).The mixture is simmered and reduced by half.it'll take several hours. Demi-glace keeps very well, about six months refrigerated or almost indefinitely frozen.
Demi mean half.glace or glaze mean icing. Some people used to Espagnole sauce instead of brown sauce. Espagnole sauce is most basic brown sauce from French cuisine.
veal stock + espagnole sauce = Demiglace sauce.