Step 1

Reduce the stock you need to thinken, skimming the top with a spoon.

Step 2

Remove from the heat and strain the sauce.

Step 3

Pour in the oil a little at a time and whisk briskly to obtain a dense, velvety sauce.

Step 4

Check that the consistency of the sauce is uniform and velvety. This sauce may be kept in the fridge for 2 to 3 days.