Season steak (chuck roast) with salt and pepper.
Seal in bag and cook at desired temp for 12 to 24 hours
To a small pot add bag juices (or beef stock), wine and pinch of black pepper. Reduce to 1/3.
To a pan add 3 Tablespoons of oil, shallots and mushrooms. Cook until they start to get some color.
Make a roux by adding flour to the shallots and mushrooms, reduce flame cook until the flour is slightly browned.
Strain the reduced liquid into the roux, adjust consistency of the liquid with water or beef broth. Taste for seasoning.
Sear steak on one side and flip.
Add 1 Table spoon butter to sauce and shake pan in incorporate.
When the steak is seared on both sides remove from the heat. Carve (no need to rest) and serve with sauce.
For printable recipe: Chuck Roast Steak with Mushroom Sauce / Sous Vide