Preheat a sous vide cooker to desired final temperature. (See note for temperature and timing charts, or find the same charts here .) Season steaks generously with salt and pepper. Place in sous vide bags along with herbs, garlic, and shallots (if using) and distribute evenly. Seal bags and place in water bath for desired time according to charts.
Place the fajitas in a large skillet and heat them up over medium heat. Season the meat with salt and cook it for 3 to 4 minutes, or until it is brown and cooked through. To serve, place the fajitas on a plate topped with sour cream, salsa, and shredded cheese.
Flank steak, also called bavette or London broil, is a flat steak cut from the underbelly and right behind the cow’s chest. When removed from the underbelly, it is removed in one flat piece of meat, ready to be placed on the grill as it is, or you can cut it into separate pieces of steak. The flank steak is a thin, flat steak that grills fast.
(boneless and defatted), top loin steak, top round steak, and top sirloin steak. Cuts were assigned randomly to the following external fat trim levels: 0.0 cm (0 inch trim), 0.3 cm (1/8 inch trim), or