To dry brine the pork, first dry the trimmed pork tenderloin thoroughly. Sprinkle the meat on all sides with the salt and pepper and place pork on a wire rack over a roasting pan. Refrigerate uncovered for 3 hours.

After 3 hours, mix the mustard, sage, rosemary, and dried ginger together in a small bowl. Remove the pork from the refrigerator and coat with the herb mixture. Return the pork to the rack and refrigerate for another hour (or up to several hours).

Preheat the oven to 425°F.

Remove the roasting pan with the pork from the refrigerator 30 minutes and let it sit at room temperature before putting it in the oven. Once the oven is up to temp, place the roasting pan in the hot oven and cook the pork loin until the internal temperature reaches 145°F on a meat thermometer. This will take about 25-35 minutes. The cooking time will depend on the thickness of the meat, so we highly recommend using an instant-read thermometer to make sure it is cooked properly. Let the pork rest for 7-10 minutes before slicing.

While the pork is roasting, heat the olive oil in a saucepan over medium heat. Add the shallots and cook until they just start to brown.

Gently crack the juniper berries by smashing them with the flat side of the blade of a kitchen knife. Don’t crush them completely, just crack them a bit so they can release their flavor. Add the wine, port, peppercorns, and juniper berries to the pan and bring to a simmer. Turn the heat down slightly and reduce the liquid by half.

Once reduced, strain the mixture and discard the solids. Return the liquid to the saucepan and reduce until you have about 6 tablespoons of liquid remaining. Up to this point, you can make this part of the sauce in advance if desired, just reheat gently before moving to the next step.

While the pork roast rests on a cutting board, remove the reduced sauce from the heat and whisk in the butter one cube at a time until fully incorporated. If the sauce is not warm enough to melt the butter you can return to a low heat, but do not use high heat or bring the sauce to a boil. This is more of a reduction sauce mounted with butter than a butter sauce, so it is less delicate and somewhat thinner than a butter sauce.

Taste and adjust the amount of salt if needed and serve the sauce over your sliced pork tenderloin. Enjoy!