How Do You Make A Simple Mustard Sauce?
• Melt butter in the saucepan over low heat and add the mustard. Stir until fragrant (about half a minute). • Add the flour and stir until smooth. Cook gently just until it has turned a slightly lighter color as the roux has started to cook. • Add the milk gradually in about 6 batches, stir each time until incorporated. If using a whisk, you can add it in two batches but multiple batches is better with wooden spoons to avoid lumps. • Stir until thickened and season to taste. If it tastes slightly floury, the sauce has not finished cooking. Continue simmering and stirring for another minute or two until it the floury taste is cooked out. Add the parsley at this stage if you included it. Serve poured over the meal. It can be kept warm easily up to 20 minutes in a bain marie as it may thicken more as it cools.