• Melt the butter in a saucepan over low heat, remove from the stove and stir in the flour. Return to the stove.
• Cook over low heat, stirring continuously to make a white roux approximately 3 minutes.
• Remove from the stove and gradually add hot but not boiling stock, stirring all the time.
• Add the mushrooms if desired.
• Return to the stove, bring to the boil, then simmer for 10 minutes.
• Strain through a fine sieve and season with salt and lemon juice.
• For a richer sauce, add the egg yolk and cream: Whisk the egg yolk and cream together in a bowl.
• Add 25 ml of the hot sauce to the egg mixture, whisking all the time.
• Pour the egg sauce mixture into the saucepan in a thin stream, whisking continuously.
• Return the saucepan to the stove, bring to boiling point and serve immediately.

Notes

• The mushrooms are optional but give extra flavour. Use 3 to 4 mushrooms for every 250 ml stock.
• Use butter rather than margarine for a richer taste.
• Do not allow a Velouté Sauce to boil after adding the egg and cream.