Bring a large pot of salted water to the boil. Add green beans and cook for 4 minutes or until crisp tender. Remove to a bowl of ice water. Add potatoes to boiling water and cook for 10 minutes or until fork tender. Drain and let cool. Cut the potatoes and green beans into 4 pieces.
Combine all vinaigrette ingredients in a food processor and process until smooth. Toss with eggs, tomatoes, potatoes, beans and olives.
Heat olive oil in a medium skillet until shimmery. Add tuna medallion and sear for 1 minute on each surface. Thinly slice and serve over salad.