COOK and stir onions in hot oil in large skillet until tender. Add tomatoes, carrots and chicken broth; mix well. Bring to a boil on medium-high heat. Reduce heat to medium-low; simmer 15 min. or until vegetables are tender, stirring occasionally.

TRANSFER vegetable mixture to a blender container in small batches; cover. Blend until smooth, adding dressing to the last batch. Serve warm or chilled.