Cook haricots verts in a small amount of boiling water 2 minutes or until crisp-tender. Drain beans and immediately plunge into ice water to stop the cooking process. Drain and set aside.
Cook potatoes in boiling water to cover about 15 minutes, or until fork-tender. Drain and cool, then cut into quarters. Drizzle with 2 tablespoons Garlic Vinaigrette; set aside.
Place eggs in a single layer in a small saucepan; add water to cover eggs by 1 inch. Cover and bring to a boil over high heat. Remove from heat and let stand, covered, in hot water 15 minutes. Immediately pour water off and rinse eggs in cold water. Tap eggs gently and peel under cold running water. Cut into quarters; set aside.
Line a serving platter or individual plates with lettuce. Arrange haricots verts, potatoes, eggs, tuna, fennel, onion, tomatoes, olives, and anchovies, if desired, over lettuce in a decorative pattern of your choice. Sprinkle with capers. Serve with Garlic Vinaigrette.
In a food processor, pulse together all ingredients except oil until well blended. With the processor on, pour in oil in a thin, steady stream until smooth.
Yield: about 1 cup.