Real Simple Magazine December 2004/January 2005. When it comes to entertaining, beef tenderloin is always a perfect answer to most menu questions. What to serve at the party? Beef cocktail sandwiches. What to serve at a brunch? Sliced beef with a savory sweet potato galette. What to serve for a holiday dinner? Classic fillet with bernaise sauce. No matter who's at the table - boss, relative, friend - a roasted fillet of beef can be dressed up or down to suite the occasion. The little black dress of meats, it's always classic and practically foolproof. Beef tenderloin is best served rare - 130 degrees F on a meat thermometer. When buying a fillet, request it trimmed and tied. If you have to tie it yourself, tuck a few inches of the thinnest end of the fillet under, then wrap it with butcher's twine at 2-inch intervals.