Originally Posted by Andy M.
Typically you reduce with the booze. It gives time for some of the alcohol to burn and cooks off the raw alcohol flavor. Then comes the broth, which is the liquid that makes the sauce.
Will it work either way? Sure.
Andy's got it right. It does work either way, but the "classical" way is to add the alcohol, and reduce it to almost a syrup. Then add your stock and reduce that whole think by half to two-thirds. and the flavor is better done that way, I think.