2 cups (16 ounces) Guinness stout (we used Rogue Chocolate Stout, which added a nice chocolatey-coffeey flavor)
1/2 cup packed light brown sugar
1 1/2 tablespoons coriander seeds, crushed
1/2 teaspoon black peppercorns, crushed
16 rib lamb chops (buy separately or buy two 8–rib racks of lamb and cut them yourself into individual chops) (we used lamb loin chops, which already come in individual chops)
Bring stout, sugar, coriander seeds, peppercorns, and 1/4 teaspoon salt to a boil in a 2–quart nonreactive saucepan, stirring until sugar is dissolved, then continue boiling (keep an eye on it and reduce heat to keep it from boiling over) until glaze is syrupy and reduced to about 1/2 cup, 20 to 30 minutes.
Strain through a fine-mesh sieve into a bowl and discard solids.
Pat chops dry and sprinkle with 1 teaspoon salt and 1/2 teaspoon black pepper.
Divide glaze between 2 small bowls and set 1 aside for use later. Brush both sides of chops with glaze (from remaining bowl) and arrange on rack of a broiler pan.
Broil 5 inches from heat, 4 to 5 minutes on each side for medium rare. (Don't hesitate to cut and peek to check on the doneness of the meat.)
Transfer chops to a platter and drizzle with reserved glaze.