Preheat your oven to 375°F (190°C). Lightly oil a baking dish or line it with parchment paper for easier cleanup.
Sauté the Aromatics
Heat 1 tablespoon of olive oil in a skillet over medium heat. Add the chopped onion and sauté until translucent, about 5 minutes. Add the minced garlic and chopped sage, cooking for another minute until fragrant.
Make the Stuffing
Transfer the sautéed mixture to a bowl. Stir in the chopped dried cranberries and breadcrumbs. Pour in the chicken broth and mix until the stuffing is moistened but not soggy. Season with salt and pepper. Set aside to cool slightly.
Butterfly the Pork
Place the pork tenderloin on a cutting board. Using a sharp knife, make a lengthwise cut down the center, being careful not to cut all the way through. Open it up like a book. If necessary, pound the pork lightly to an even thickness (about ½ inch) using a meat mallet or rolling pin.
Fill and Roll
Spoon the stuffing mixture evenly down the center of the pork. Roll the tenderloin tightly from one side to the other, keeping the stuffing inside. Secure the roll with kitchen twine every 1-2 inches.
Sear (Optional but Recommended)
Heat a little oil in a large oven-safe skillet or pan over medium-high heat. Sear the pork roll on all sides for about 1-2 minutes per side until lightly browned. This step locks in flavor and gives a beautiful crust.
Roast the Pork
Place the seared pork in your prepared baking dish. If using the glaze, mix the Dijon mustard, maple syrup, and balsamic vinegar in a small bowl, and brush it generously over the pork.
Roast in the oven for 35–40 minutes or until the internal temperature reaches 145°F in the thickest part.
Rest and Serve
Remove the pork from the oven and tent loosely with foil. Let it rest for 10 minutes before slicing into medallions. This allows the juices to redistribute, keeping your cranberry stuffed pork loin moist and flavorful.