Fragrant truffle juice gives the sauce for our Cote de Boeuf Rossini a certain je ne sais quois.
In a large nonstick skillet, heat the oil over high. Season beef with salt and pepper. Working in batches if necessary so as not to crowd the pan, brown the beef, about 3 minutes per side.
Reduce heat to medium, then add peppercorns and shallots. Cook, stirring, 10 minutes. Add wine and cook, stirring up any browned bits on the bottom of the pan with a wooden spoon, until the liquid has almost evaporated. Add stock, truffle juice, and parsley stems. Bring to a boil, then cook until reduced by one-half. Strain through a fine mesh sieve. Season with salt and pepper.