Albert , chef who, with brother Michel, opened restaurant Le Gavroche in London in 1967 (4)

(Other definitions for roux that I've seen before include "Mixture of flour and fat for cooking" , "Mixture of fat and flour used for thickening sauces" , "Butter and flour sauce combination" , "Fat and flour mixture, cooked and used to make sauces" , "sauce mix" .)