1. Cook pasta according to package directions, omitting salt and fat. Add broccoli to cooking water 1 minute before pasta is done. Drain pasta and broccoli well; transfer to a large bowl, and add green onions and red bell pepper. Set aside, and cool slightly.
2. Combine vinegar and remaining 5 ingredients; stir well. Add vinegar mixture to pasta mixture, stirring well. Serve at room temperature.