How to Make It
Cook pasta in a large pot of boiling salted water until al dente, 8 to 10 minutes. Using a slotted spoon, remove pasta, and reserve cooking water in pan. Add potatoes and bring to a simmer over medium-high. Cook potatoes until tender, about 8 minutes. Using a slotted spoon, remove potatoes, reserving cooking water in pan. Carefully lower eggs into pan, and return to a simmer. Cook 12 minutes. Remove eggs from pan, and transfer to a bowl of ice water until cool, about 10 minutes. Peel eggs and cut into quarters.
Whisk together oil, vinegar, mustard, and soy sauce in a large bowl. Add pasta, potatoes, tuna, beans, radishes, olives, parsley, and remaining 1 teaspoon salt and toss to combine. Serve topped with eggs and more parsley.