Fill a large pot with lightly salted water and bring to a rolling boil over high heat. Stir in the pasta, and return to a boil. Cook uncovered, stirring occasionally, until the pasta is cooked through, but still firm to the bite, about 8 minutes. Rinse with cool water; drain well in a colander set in the sink; set aside to cool completely.
Place a steamer insert into a saucepan, and fill with water to just below the bottom of the steamer. Cover, and bring the water to a boil over high heat. Add the broccoli, recover, and steam until bright green and still crisp, about 2 minutes. Remove the broccoli and rinse well with cold water until cold; drain.
Stir together the onion, green bell pepper, red bell pepper, the cooled pasta, and the cooled broccoli in a large bowl. Whisk together the mayonnaise, red wine vinegar dressing, and dry mustard. Pour the dressing over the pasta and vegetables; stir to combine. Cover and refrigerate overnight.
