What is duxelle or duxelles (pronounced duck-SELL)?
Duxelles is a finely chopped (minced) mixture of mushrooms or mushroom stems, onions, shallots and herbs sautéed in butter, and reduced to a paste (sometimes cream is used, as well). It is a basic preparation used in stuffings and sauces (notably, beef Wellington) or as a garnish. Duxelles can also be filled into a pocket of raw pastry and baked as a savory tart.
Duxelles is said to have been created by the 17th-century French chef François Pierre La Varenne (1615–1678) and to have been named after his employer, Nicolas Chalon du Blé, marquis d'Uxelles, maréchal de France.
Try Gordon Ramsay's Beef Wellington recipe which calls for making a duxelles (or mushroom paste).