1. In a 5-quart pot, bring 1/2 inch water to a boil; add salt and new potatoes. Cover; cook, turning occasionally, until tender, 14 to 16 minutes.
2. With a slotted spoon, transfer potatoes to a bowl. Toss with rosemary, oil and salt to taste. Set aside to cool. Add green beans to the pot of boiling water. Cover; cook, stirring occasionally, until tender, 4 to 6 minutes. Remove with a slotted spoon. Rinse under cool water, and set aside.
3. Fill a deep skillet with 1/4 inch water. Season salmon on both sides with salt and pepper; place in skillet. Bring water to a gentle simmer; cover, and cook until salmon is opaque throughout, 10 to 12 minutes. Transfer to a plate; flake with a fork, and let cool.
4. While salmon is cooking, tear lettuce into pieces, quarter potatoes and tomatoes, peel and quarter eggs, and thinly slice onion.
5. On a large platter (or four serving plates), arrange lettuce, salmon, green beans, potatoes, eggs, tomatoes, onion, anchovies (if using), and olives.
6. Whisk the juice, mustard and salt in a medium bowl until combined. While whisking constantly, slowly drizzle in oil. Season with additional salt and pepper to taste. Serve salad with Dijon Vinaigrette on the side.