Cider-Brined Mustard-Glazed Pork Loin

Bring salt, brown sugar, peppercorns, coriander seeds, mustard seeds, thyme, bay leaves, 2 cups apple cider, and 2 cups water to a low boil in a medium saucepan over medium heat. Cook, whisking, until sugar and salt dissolve, about 4 minutes. Transfer brine to a large bowl and add remaining 2 cups apple cider and 2 cups ice. Let cool to room temperature.

Place pork and brine in a large resealable plastic bag; turn to coat. Seal and chill at least 8 hours.

Remove pork from brine and pat dry with paper towels. Let sit at room temperature 1 hour.

Place rack in lower third of oven; preheat to 400°F.

Season pork all over with salt and pepper. Heat oil in a large skillet over medium-high. Sear pork, turning occasionally, until browned on all sides (including ends), 10–12 minutes.

Meanwhile, combine mustard, brown sugar, syrup, and thyme in a medium bowl.

Pour apple cider into a large roasting pan or glass baking dish. Transfer pork, fat side up, to pan. Brush all over with mustard mixture. Roast pork, basting every 15 minutes, until an instant-read thermometer inserted into the center registers 140°F, 50–70 minutes.

Transfer to a cutting board and let rest at least 15 minutes before slicing.

Pork can be brined up to 24 hours ahead. Keep chilled in plastic bag.