I don’t often grill or char vegetables; gentle cooking methods are considered most health supportive, as they preserve nutrients. But once in a while it is a lovely alternative to steaming, and the grill marks do add a note of festivity. If you cannot find fresh tarragon, use finely chopped, fresh marjoram or thyme, and add a pinch of ground aniseed. You can make the dressing and grill the vegetables in advance, but keep the elements separate until serving.