In a saucepan, add 2 cups chopped rhubarb, ½ cup sugar, and ¼ cup vinegar. Combine and cook over medium heat until the rhubarb is tender, about 6 minutes. Discard the pulp, reserving about 6 tablespoons of juice.
Pour juice into jar, add ¾ cup oil, 3 tablespoons grated onion, 1½ teaspoons Worcestershire sauce, and ¼ teaspoon salt. Shake well. Refrigerate for at least 1 hour.
Just before serving, combine salad ingredients in a large bowl. Add the dressing and toss to coat.