Sauce Périgueux

In a heavy pot heat the fat, stir in the shallots and onion and cook over a low fire until soft but not brown. Stir in the flour and cook over a low fire, stirring constantly until just beginning to brown. Stir in the wine, broth and a little salt and pepper. Bring to a boil and simmer uncovered, stirring occasionally, for 1 hour or until reduced by half. Strain into a clean pot. Stir in the tr