When I was working in Paris as a cook in 98-01 sous vide was becoming all the rage. I did a one week course on sous vide cooking at LeNotre where we did their equivilant of a brisket cut, sous vide. Tonight, I did a similar recipe except it was with flank steak.
I had too decent sized flank steaks and trimmed them up the best I could to cut off any fat or silver skin from the meat. Next I sliced two onions in to thin pieces and cooked them down until they were soft and carmelized. I also included maybe one or two cloves of garlic in that mixture. While I was doing that, I had a full bottle of red wine, cheap enough to cook with but still decent enough to drink and reduced taht by at least 50%. Then I added the wine to the mixture, seasoned the steaks with salt and bagged them up individually. I put in the demi at 130 for 24 hours, took them out, put the meat aside and strained the onions, thyme twigs, etc. and started to reduce the cooking liquid and wine mixture. I made a beurre marnier, added it and cooked it for around 30 minutes to ensure the flour was cooked.
When my guests came over, I tossed the steaks on the egg at 700 degrees. The steaks and my sauces were perfect. This was the best thing I've made so far in the demi. YUM!