In a saucepan, combine the 3 cups apple cider, 1 cup water, ⅓ cup Kosher salt, smashed garlic cloves, rosemary and thyme sprigs, bay leaves, cinnamon sticks, and black peppercorns.

Bring to a boil, then reduce to a simmer for about 5 minutes, allowing the flavors to meld.

Remove from heat and stir in 1 cup of cold water and the ice cubes to cool the brine completely.

Transfer to a shallow container to speed up the cooling process; it must be completely cooled before adding the pork.

Once the brine is completely cooled, transfer to a container or brining bag, ensuring it can fully cover the pork.

Add the pork loin to the brine, cover tightly, and refrigerate for about 16-18 hours. Do not exceed 20 hours.

Preheat your oven to 375ºF.

After brining, remove the pork and pat it dry completely with paper towels.

Brush with Dijon mustard and season with fresh minced herbs, 2 teaspoons Kosher salt, and 1 teaspoon ground black pepper.

Tie with kitchen twine for even cooking, if desired.

In a large cast-iron skillet over medium heat, drizzle with olive oil and sear the pork on all sides until golden brown (3–4 minutes per side).

Remove the pork from the skillet and deglaze the pan with a splash of chicken broth.

Return the pork to the skillet and transfer it to the oven. Roast uncovered for 25 minutes.

In a bowl, whisk together ½ cup maple syrup, 2 tablespoons Dijon mustard, 2 tablespoons apple cider vinegar, and a pinch of salt. Set aside.

After 25 minutes, remove the pork from the oven and arrange the quartered apples, onion slices, split garlic heads, and fresh herb sprigs around it.

Pour about ½ cup chicken broth over the veggies and apples, and brush some of the maple-cider glaze over everything.

Return to the oven and roast for another 30-35 minutes, brushing with the glaze a few more times.

Remove when a meat thermometer reads about 150ºF. Let the pork rest for at least 15 minutes before serving.