A 'vegetable trivet' refers to a selection of vegetables, often carrots, onions, celery, which are used as a bed for meat as it braises or roasts. The vegetables serve to impart flavour on the main ingredient as it cooks and can also be used to make a sauce for the final dish. Make sure to cut the vegetables into large wedges, if they are cut too finely they will disintegrate during the long cooking time.