"First I melted the butter in a pan, then added the flour and stirring constantly, cooked for about five minutes. Then added the beef stock, salt and pepper and cooked for a few minutes. Then added the cream. So what was the problem? I used sour cream, because I didn't want my sauce to be sweet, I wanted a sour sauce and the consistency of sour cream is different.

I might be wrong too.. I just take literally from this passage.