1. Preheat oven to 450°.
2. Place onion halves, cut sides down, in a baking dish coated with cooking spray. Bake, uncovered, at 450° for 30 minutes or until tender. Cool slightly; coarsely chop, and set aside.
3. Trim ends from wax beans, and remove strings. Cook black-eyed peas and lima beans in boiling water 4 minutes. Add wax beans; cook 8 minutes or until tender. Drain.
4. Combine vinegar and next 6 ingredients in a large bowl; stir well with a whisk. Add onion, peas, and beans; toss to coat. Cover and marinate in refrigerator at least 8 hours.
carbo rating: 18