Cabernet Sauvignon Reduction

This is very easy and I'm willing to bet it's similar to what is sold in Williams-Sonoma (no idea, since I didn't get the chance to buy any, and now, probably never will).  I forgot to get a final pic, so I'll have to add that in later.

http://winefolly.com/update/red-wine-reduction-sauce-recipe/

1 T. butter
1 small shallot, minced
1 T. flour
3/4 c. Cabernet Sauvignon
1/4 c. balsamic vinegar
1 sprig fresh rosemary
salt and pepper, to taste

Instructions:

1. In a medium skillet, melt butter over medium heat.  Add shallot and flour.  Cook, stirring constantly, for 3 minutes.

2. Add wine, vinegar, and rosemary.  Bring to a simmer and allow to simmer until reduced by half; this does not take long, so watch carefully (think it was 3-5 minutes at most for mine).

3. Add salt and pepper if desired (I did not, since I was using in another recipe).  Remove rosemary sprig and strain if desired (I did).