Cover potatoes with cold water in a medium saucepan, season with salt and bring to a boil. Reduce heat to medium and cook until the potatoes are just tender, about 10 minutes. Drain. Let stand until cool enough to handle. Slice into a large bowl and toss with 1/4 cup dressing.
Cook green beans in boiling salted water until just tender, about 5 minutes. Drain, refresh under cold water and pat dry. Add to the potatoes along with another 1/4 cup dressing. Toss gently to coat.
Transfer to a platter or individual plates. Arrange tomatoes and eggs around the outside; scatter tuna, olives, onions, capers and parsley over the top. Arrange anchovies decoratively; drizzle with the remaining dressing.
Roasted Garlic Dressing
1 starch, 4 vegetable, 2 lean meat, 1 fat