In jar with tight-fitting lid, combine all Dressing ingredients; shake well. Set aside.
Cook tortellini, carrots and green beans as directed on tortellini package until tortellini are tender and vegetables are crisp-tender. Drain; return to saucepan. Cover with cold water; let stand 5 minutes. Drain well.
In medium bowl, combine tortellini, carrots and green beans; add onions. Pour dressing over salad; toss gently to coat.