Follow the package directions to cook the pasta, then drain and rinse under cold water. Transfer into a big bowl, then put in onions, tomatoes, cucumber, carrots, broccoli and cheese. Mix together the salt, mustard, onion, garlic, sugar and vinegar in a blender, then pour the oil slowly and blend until smooth. Put poppy seeds, then pour over pasta mixture and toss. Cover and chill for a minimum of 1 hour.