In a jar with a tight fitting lid, combine white balsamic vinegar, lemon juice, salt, pepper, mustard, shallots and olive oil. Tighten lid and shake well to mix.
Prepare salad:
Boil eggs. Place eggs in a large saucepan and cover with at least an inch of water. Bring water to a boil. Top pan with a lid and turn off heat. Let eggs sit for 15 minutes. Then, drain them and place them in a bowl of ice water for 10 minutes. Peel eggs and slice into quarters.
Boil potatoes: Cut potatoes into quarters. Place potatoes in a medium sized sauce pan and cover with water. Add salt to taste. Bring to a boil and cook until they just are fork tender. 10-15 minutes. Do not over cook. Drain and let potatoes cool.
Roast green beans: Follow this recipe, Roasted green beans, omitting parmesan cheese
Slice cucumbers and cut tomatoes into chunks.
Drain the tuna and the olives.
Assemble salad:
Place Spring mix on a large platter. Arrange eggs, potatoes, tuna, olives, green beans and cucumber over the lettuce.
Sprinkle with salt, pepper, parsley and dill.
Serve immediately with Lemon Vinaigrette on the side.