Place whole tenderloin (2-4 pounds) on rack in shallow roasting or broiler pan. Brush entire surface with oil. Tuck under "tail" end so roast is a uniform size. Insert meat thermometer in thickest part. Place in a preheated 425 F oven.

Cooking Time for Entire Roast: 35-40 minutes for rare (135 F meat thermometer reading when roast is removed from oven) 40-50 minutes for medium (150 F meat thermometer reading when roast is removed from oven)

Place meat on cutting board or heated platter. Cover with foil and allow to stand about 10 minutes. Pour about 1 cup liquid (water with a little dry red wine and a few drops of browning seasoning sauce) into roasting pan. Heat and stir to blend. Season with salt and pepper, if necessary; strain.

To Serve: Carve tenderloin into slices; pass hot au jus.