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1
Preheat the oven to 350.
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2
Combine all of the ingredients in a small shallow baking dish.
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3
Cover with foil and bake for 1 hour.
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4
Uncover and bake for about 30 minutes longer, or until the shallots are tender and the liquid has almost completely evaporated.
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5
Let cool to room temperature.
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6
Discard the thyme sprig.
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7
Raise the oven temperature to 400.
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8
Heat 2 tablespoons of the vegetable oil in a large saucepan.
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9
Add the mushrooms, onion, carrot, celery, garlic, sage, rosemary and thyme and cook over moderately low heat, stirring occasionally, until the vegetables start to brown, about 12 minutes.
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10
Raise the heat to high, add the wine and port and boil until reduced to 1/4 cup, about 10 minutes.
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11
Add the beef stock to the saucepan and bring to a boil.
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12
Reduce the heat to low and simmer until reduced to 2 cups, about 30 minutes.
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13
Strain the sauce into a saucepan, pressing on the solids to extract as much liquid as possible.
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14
Season the tenderloins with salt and pepper.
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15
Heat the remaining 2 tablespoons of oil in a large ovenproof skillet.
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16
Set the roasts in the skillet, smooth side down, and brown them on all sides, about 12 minutes.
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17
Turn the roasts smooth side up and spread the shallot confit on top.
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18
Transfer the skillet to the oven and roast the tenderloins for about 30 minutes, or until an instant-read thermometer registers 125 for rare.
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19
Transfer the roasts to a carving board, cover loosely with foil and let rest for 10 minutes.
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20
Set the skillet over high heat and cook until the pan juices sizzle.
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21
Whisk in the reserved port sauce and simmer for 3 minutes.
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22
Remove the skillet from the heat and whisk in the butter, 1 tablespoon at a time, until blended.
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23
Season the sauce with salt and pepper and pour into a gravy boat.
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24
Carve the roasts and serve with the port sauce.
