In the culinary arts, a liaison is a mixture of egg yolks and heavy cream that is used to thicken a sauce.
The steps for incorporating a liaison into a velouté sauce are:
- In a stainless steel or glass bowl, beat together the cream and egg yolks until smooth. This egg-cream mixture is your liaison.
- Slowly add about a cup of the hot velouté into the liaison, whisking constantly so that the egg yolks don't curdle from the heat.
- Now gradually whisk the warm liaison back into the velouté.
- Bring the sauce back to a gentle simmer for just a moment, but don't let it boil.
An example of a sauce that is made with a liaison is the classic Allemande Sauce.
Also see: How to Thicken a Sauce with Roux