Celery root—also known as celeriac—has a parsnip-like texture and mild celery-like flavor. At the grocery store, look for firm 1-pound roots that are evenly round and not too knobby; the knobs make peeling off the tough skin more challenging. Though often served raw, celery root becomes soft and tender when roasted and browning develops sweet, nutty notes. For this recipe, we cut the roots into wedges for relatively fast, even cooking and amp up the flavor with a glaze containing mirin, sugar, soy and sesame oil. But we hold off on brushing the wedges until midway through roasting to prevent scorching.