Arrange veggies on a pretty platter or board covered tightly with plastic wrap for easy transport.
Place potatoes in a medium saucepan. Add 1/4 cup salt and water to cover by 2 inches. Bring to a gentle boil over medium-high; reduce heat to low, and simmer 8 to 10 minutes or until just tender, adding haricots verts during the last 2 minutes of cook time. Drain vegetables, and plunge into ice water to stop the cooking process.
Stir together lemon juice, shallot, garlic, and mustard in a medium bowl. Let stand 5 minutes. Whisk in olive oil, olives, and parsley. Stir in 1 teaspoon salt and 1/2 teaspoon pepper.
Drain potatoes and haricots verts, and pat dry with paper towels. Arrange cooked vegetables, tomatoes, endive leaves, cucumbers, and eggs on a serving board; sprinkle with remaining 1/2 teaspoon salt and 1/4 teaspoon pepper. Serve with vinaigrette.