Put the pork loin in a leak-proof sous vide bag. Fill a large container or stockpot with water up to the fill line of the immersion cooker. Put the immersion cooker at 144 °F (62 °C) and set it to 1 hour. If your roast is frozen, add a half an hour to the time.
For the Sauce
Meanwhile, while that is happening, prep the ingredients for the sauce. Chop the onion coarsely. Heat a small skillet till smoking and add olive oil. Saute onions until translucent. Mix cranberry juice with wine and add to skillet. Cover and simmer on low heat and let the liquid reduce by a third. Add preserves to skillet and whisk constantly until sauce reduced almost to a syrup. The sauce will be glossy.
When the roast is done, heat a large castiron skillet and put a little olive oil in. Let it get to the point that the oil is shimmering. Add the pork loin and brown on both sides, 1 to 2 minutes per side. Remove from the pan and let it sit for about 5 minutes before slicing it. Serve it with the sauce.
Notes
The weight of the pork is approximate.
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