I'm preparing the court-bouillon recipe from James Peterson's Sauces (p. 103 of 3rd edition). The procedure is, roughly:
- Sweat vegetables,
- Simmer vegetables for 10 minutes,
- Add white wine and vinegar, simmering for a further 15 to 20 minutes, and then
- Cool and strain.
My question is about step 3. For what reasons would the wine and vinegar be withheld for the first 10 minutes of simmering? Is this an evaporation issue? Or is there some deeper interaction between wine/vinegar and vegetables to be accounted for?