How to Make It
In a medium saucepan, melt the butter. Add the shallot and cook over moderate heat, stirring occasionally, until softened, 2 to 3 minutes. Add the peppercorns and Cognac and cook until the liquid is reduced by half, 2 to 3 minutes. Add the beef stock and cook until reduced by half, about 5 minutes. Whisk in the cream, mustard and tamari and simmer until the sauce is thickened and reduced by one-third, about 3 minutes more. Stir in the chives, season with salt and pepper and serve immediately.