I've made an incredible wine sauce the first time I made beef bourgingon. And after many tries, I've never been able to replicate my success. The sauce kept coming out bitter even after experimenting with different wines and aromatics. I just could not for the life of me figure out what was wrong.
But now I think I understand what I keep on doing wrong. Let's say you're making a simple sauce out of stock and red wine. It's important to fully reduce the wine to a glaze 1st, and THEN add in the stock and reduce to taste, right?
What I've been doing is essentially mixing the wine and stock together and reducing the sauce from there. That's going to lead to a bitter and generally not very good sauce right? Because as you're reducing, by the time you get the right consistency and strength of taste, you haven't cooked out all the alcohol and bitterness from your wine. This seems like a good explanation for my constantly bitter wine sauce.