In a medium saucepan cook the potatoes in lightly salted boiling water, covered, for 5 minutes. Break up frozen beans and add them to the potatoes in saucepan. Return to boiling; reduce heat. Cover and simmer for 4 to 6 minutes more or until potatoes are tender and green beans are just crisp-tender; drain. Cool slightly.
In a large salad bowl combine potato-green bean mixture, tomatoes, yellow or green peppers, and olives. Pour salad dressing over mixture, tossing gently to coat. Cover and chill for 2 to 3 hours.
To serve, line individual plates with romaine lettuce. Top with vegetable mixture and hard-cooked eggs. Makes 4 servings.