For the pork chops:
¼ c. kosher salt, plus more to taste 2 T. packed lightbrown sugar
¼ c. fresh sage leaves, finely chopped
4 bone-in center-cut pork rib chops, about 1” thick Freshly cracked black pepper, to taste
2 T. vegetable oil
4 T. unsalted butter, divided
1 large yellow onion, peeled, trimmed, and cut into 1” slices
2 medium apples, such as Jonagold or Golden Delicious, cored and cut into 1” slices 1 c. apple cider
For the mashed potatoes:
4 pounds russet potatoes, peeled and cut into 1” pieces Kosher salt and freshly cracked black pepper, to taste
2 ¼ c. whole milk
1 stick unsalted butter
¾ c. sour cream
In a small saucepan, bring 2 cups of water to a simmer. Add salt, light brown sugar, and sage and whisk untilthe sugar and salt dissolve, then remove from heat and transfer to a 9x13” baking dish. Add 2 cups of cold water and allow to cool to room temperature before adding pork chops to the brine, covering, and refrigerating, 1-2 hours.
Once pork chops are ready, remove from the brine and pat dry with paper towels; discard brine. Season to tastewith salt and pepper and set aside to come to room temperature, about 30 minutes. Meanwhile, in a large pot, coverpotatoes with cold water by about an inch.
Generously salt and bring to a boil over high heat, then reduce heat and simmer, uncovered, until potatoes aretender and falling apart when pierced with a fork, 10-12 minutes. Drain potatoes in a colander, then return to pot, cover, and keep warm on the stovetop until ready to mash. In a small pot, gently warm milk and butter, being careful not to boil.
While potatoes cook, heat a 12” heavy-bottomed skillet (cast iron would be a very good choice) over medium-high. Add vegetable oil to the pan and, when shimmering, sear the pork chops until golden, flipping once, about 3-4 minutes per side. Transfer to a clean plate and loosely tent with foil.
Add 2 tablespoons butter to the pan and swirl to melt, then add the onion and apples and cook, stirring occasionally, until the onions are lightly caramelized and the apples have begun to soften, about 7-9 minutes. Deglaze the pan with the apple cider, scraping up any brown bits from the bottom of the skillet, then bring to a boil. Reduce heat to medium-low, return pork chops to the pan and simmer, flipping once halfway through, until a meat thermometer inserted into the center of the chops reaches 140 degrees, about 8-10 minutes more. Remove the pork chops andallow to rest, loosely tented with foil, and continue cooking until the onion- apple mixture is tender and golden and thecider has reduced by half, about 5 minutes longer. Stir in the remaining butter and taste, adjusting seasoning as necessary.
While pork chops are simmering, finish mashed potatoes. Over low heat, add milk and butter mixture a little at a time, mashing potatoes until smooth and creamy. Season generously with salt and pepper, then stir in sour cream. Taste and adjust seasoning, then serve alongside pork chops, topped with the onion-apple mixture and the ciderpan sauce.