Pistachio-Crusted Grilled Rack of Lamb with a Carrot-Ginger Essence

Both the mustard-brown sugar glaze and the carrot-ginger essence can be made 2 days ahead of time and held, covered, in the refrigerator. Patrick serves these chops with toasted whole shelled pistachios and Brussels sprout leaves cooked 5 minutes in boiling salted water, buttered, and seasoned.