Robert Sauce

Ingredients

• 1 large onion, finely chopped
• 2 décilitres dry white wine
• 3 décilitres demi-glace (rich brown sauce reduction)
• 1 pinch powdered sugar
• 1 tablespoon mustard

Instructions

1. Sweat (cook gently in butter over low heat without browning) the finely chopped onion in butter. Deglaze the pan with the white wine and reduce by two-thirds.
2. Add the demi-glace and simmer gently for 10 minutes.
3. Strain the sauce through a fine-mesh sieve (chinois), or leave it unstrained as preferred. Remove from heat and season with a pinch of powdered sugar and the mustard, stirring to combine. Do not allow the sauce to boil after the mustard has been added.