1Cook frozen cauliflower as directed on bag. Cook frozen peas as directed on box; drain. Place cauliflower and peas in large bowl; refrigerate.
2In tightly covered container, shake vinaigrette ingredients until well blended. Stir tuna, cucumber and green onions into cauliflower mixture; add vinaigrette. Toss to coat. Cover; refrigerate about 1 hour or until chilled.
3Just before serving, top with olives and tomatoes.