1 (1/2-lb) piece venison tenderloin (1 1/2 inches in diameter), trimmed, at room temperature for 30 minutes
1/2 teaspoon coarsely ground black pepper
1/2 teaspoon salt
11/2 tablespoons vegetable or olive oil
1/4 cup finely chopped shallot
1/4 cup Madeira wine
1/3 cup beef or veal demi-glace
1 teaspoon drained green peppercorns in brine, coarsely chopped
1 teaspoon unsalted butter
Put oven rack in middle position and preheat oven to 425F.
Pat venison dry and sprinkle with black pepper and 1/4 teaspoon salt. Heat oil in an ovenproof 12-inch heavy skillet over moderately high heat until just smoking, then brown venison on all sides (except ends), about 3 minutes total.
Transfer skillet with venison to oven and roast until thermometer inserted diagonally 2 inches into center registers 115F, 4 to 5 minutes. Transfer venison with tongs to a plate and let stand, loosely covered with foil, 5 minutes (temperature will rise to 125F for medium-rare).
While meat stands, add shallot to skillet (handle will be hot) and cook over moderate heat, stirring, until golden, about 2 minutes. Add Madeira and deglaze skillet by boiling, stirring and scraping up brown bits, until liquid is reduced by half, about 1 minute. Add demi-glace and boil, stirring, until sauce is slightly thickened, about 1 minute. Stir in peppercorns, butter, remaining 1/4 teaspoon salt, and any meat juices that have accumulated on plate, then remove from heat.
Cut venison into 1/2-inch-thick slices and serve with sauce.
Beef tenderloin can be substituted for venison. Use 1 (3/4-lb) filet mignon (3 inches in diameter). Brown on all sides (including ends), about 5 minutes total, then roast until thermometer inserted into center registers 120F, 18 to 20 minutes. Let stand, loosely covered with foil, 10 minutes (temperature will rise to 130F for medium-rare). Pour off all but 1 tablespoon fat from skillet before making sauce.
Makes 2 servings.