I will be a rock star in my boss's eyes if I can tell him what is in his favorite sauce of all time. He had entrocote sauce on his steak in Paris and wants more, NOW. He dicsribes it as a brown sauce...my research - what little I could find- tells me it is a butter based sauce.
Does anyone out there know what is in the sauce and how to make it. Many, Many, Many thanks in advance.