How to Make It
Combine warm water, 1/3 cup sugar, mustard seeds, bay leaf, and 1/3 cup of the salt in a large bowl; whisk until salt and sugar dissolve. Add pork chops, submerging completely; cover and chill 1 1/2 hours. Remove pork from brine; discard brine. Pat pork chops dry, and sprinkle with 3/4 teasoon black pepper and 1 1/2 teaspoons salt.
Heat oil in a large skillet over medium-high. Cook pork chops until browned, 3 to 4 minutes per side. Remove chops from skillet. Add onions; cook, stirring occasionally, until softened, about 6 minutes. Add apple cider. Cook until reduced slightly, about 2 minutes. Transfer onion mixture to a 6-quart slow cooker; stir in chicken broth and mustard. Place pork chops on top of onion mixture. Cover and cook on LOW until pork chops are tender, about 4 hours.
At the end of the pork cooking time, preheat the oven to 450˚F. Toss sweet potato rounds with 2 tablepsoons olive oil, 1 teaspoon kosher salt, and 1/2 teaspoon black pepper. Bake in the preheated oven until tender, about 25 minutes.
Meanwhile, cook the butter in a small skillet over medium until foam subsides and butter is golden brown, about 4 minutes. Immediately transfer butter to a medium bowl. Add the golden raisins, sherry vinegar, and 3/4 teaspoon granulated sugar; stir to dissolve sugar. Let stand 10 minutes. Stir in the parsley, olives, and 2 tablepsoons olive oil.
Slice the pork chops. Divide the cooked couscous evenly among 4 plates; top with sliced pork and relish, and serve with sweet potatoes.