Place all of the ingredients in a jar, seal with a lid, and shake until completely combined. Set aside.Roast the Vegetables:
Preheat oven to 400°F (200°C). Line a large rimmed baking sheet with cooking spray and set aside.
Place potatoes in a large zip top plastic bag. Add 1 tablespoon of olive oil, ¼ teaspoon garlic powder, and ¼ teaspoon salt. Toss gently to coat all of the potatoes evenly with the oil and seasonings.
Spread potatoes onto prepared baking sheet (save the plastic bag so that you can use it again with the green beans). Roast the potatoes in the oven for 15 minutes, stirring once.
While the potatoes are in the oven, place the green beans in the large zip top plastic bag. Add 1 tablespoon of olive oil to the bag, along with ¼ teaspoon salt. Toss gently to coat the green beans in the oil and salt.
After the potatoes have been roasting for 15 minutes, remove the baking sheet from the oven. Spread the green beans onto the baking sheet with the potatoes in a single layer.
Return the baking sheet to the oven and roast potatoes and green beans for about 10-15 more minutes (stirring halfway through), or until vegetables are tender. Keep an eye on the potatoes, because very small potatoes will be done in about 20 total minutes, while larger potatoes will need closer to 30 minutes. They should be crispy on the outside and soft on the inside.
Set vegetables aside to cool slightly while you assemble the rest of the salad ingredients.Assemble the Salads:
Divide lettuce greens evenly among serving bowls.
Top each bowl of lettuce with tomatoes, hard-boiled eggs, olives, anchovies, tuna, roasted potatoes and green beans. Drizzle with vinaigrette and garnish with fresh parsley.
Notes
Cooking Just for Two? Cut the ingredients in half and only prepare two salads.