In medium saucepan, combine broth, 2 cups water and sun-dried tomatoes. Bring to a boil. Stir in couscous; remove from heat. Cover; let stand 5 minutes.
Line 1 large or 2 small cookie sheets with waxed paper. To cool couscous mixture quickly, fluff with fork; spread on lined cookie sheet. Let stand 5 minutes.
In large bowl, combine cooled couscous mixture, onions, basil, olives, balsamic vinegar and 2 tablespoons water; toss gently to mix well. Add oil; toss gently. Serve immediately, or cover and refrigerate until serving time.