That sounds right to me. Filet of beef only, mushrooms, butter, a shallot, black pepper, a little salt to taste although salted butter will usually accomplish that, sour cream.

Traditionally should be prepared in a chafing dish tableside.....

There's some debate about what goes atop the dish.....Paprika only, chopped parsely or chopped scallion tops. The first two are likely permissible with the paprika more "authentic", but chopped scallions does change the flavor.

NO SOUP!