Add 1 at a time through the feed tube of a running blender, vinegar, shallot, salt, pepper, tahini, and sesame seeds. Leaving the blender running add the oil in a slow thin stream. Set aside briefly.
Toss greens, corn, orange, bell pepper, water chestnuts, and tomatoes together in a large bowl with enough dressing to coat. Serve with additional dressing on the side.