PREPARATION:
- Preheat oven to 400°F. Spray jelly-roll pan with nonstick cooking spray.
- Scrub potatoes; pat dry. Cut potatoes into 1/2-inch cubes. Place on prepared pan; coat potatoes with cooking spray. Arrange in a single layer. Bake 20 to 25 minutes or until potatoes are tender and lightly browned, stirring occasionally.
- While the potatoes are baking, combine oil, orange juice, lemon juice, mustard, salt and pepper in small bowl. Whisk until well blended.
- Place potatoes in large bowl; cool slightly. Add tuna, tomatoes, green onions and oil mixture; toss gently to coat. Cover and chill at least 1 hour or up to 24 hours.
- Let salad stand at room temperature 10 minutes. Toss gently and serve on lettuce leaves.
