Brined Pork Chops
In a large pot over medium heat, combine the apple juice, water, sugar, salt, black pepper, and red pepper flakes. Bring to a boil, stirring occasionally to dissolve the dry ingredients, and continue boiling for a few minutes. Meanwhile, put 2 cups of ice cubes in a large heatproof bowl. Remove the brine mixture from the heat and carefully pour it into the bowl with the ice.

Once the brine has cooled to room temperature, add the pork chops, cover, and refrigerate for at least 4 hours or up to 24 hours.

Seasoning and Grilling
Before cooking, remove the chops, rinse them, pat dry with paper towels and leave at room temperature while you heat a grill to medium-high heat, 450°F..

In a small bowl, stir together the pepper, salt, onion powder, coriander, and red pepper flakes. Sprinkle one side of the chops with about ½ tablespoon of the seasoning mixture. Oil the grill grid and place pork chops on it seasoned side down; then season their tops. Cook until the undersides are nicely browned, about 4 minutes. Turn over the chops and cook another 2 to 3 minutes. Remove the chops to a platter, top each one with a teaspoon of the butter, cover with heavy-duty aluminum foil, and leave to rest for about 5 minutes before serving.