PLACE THE EGGPLANT in a shallow heat-proof dish and steam over high heat for about 20 minutes or until tender. Test with a fork. Remove. When cooled, tear into thin strips or cut into a 1/2-inch cubes. Refrigerate. In a bowl, cover the optional agar-agar with cold water for 10 seconds or until pliable. Drain, cut into 1-inch lengths and refrigerate. In a small bowl, thoroughly mix together the vinaigrette ingredients. Taste for seasoning. Arrange the agar-agar in a shallow platter. Toss the chilled eggplant with the vinaigrette and scatter over the agar-agar. Garnish with a sprig of coriander and the toasted sesame seeds.