Robert Onion, white wine, Espagnole and mustard stirred in at the end. One of the oldest named sauces in the French repertoire. 150 g — onion 30 g — butter 150 ml — dry white wine 350 ml — brown stock 25 g — Dijon mustard 3 g — sugar Cook the finely chopped onion in butter until golden but not brown, about fifteen minutes on a medium-low heat. Add the wine, reduce by half, add the Espagnole and simmer fifteen minutes. Stir the mustard in off the heat with the pinch of sugar. Grilled pork chop, sausages, boiled beef, roast goose.