1. To make the dressing, combine all vinaigrette ingredients in squeeze bottle or jar and shake well to incorporate. Set the dressing aside while preparing the salad so the flavors can marry
2. Halve the potatoes, place in a large saucepan, add water to cover and a nice pinch of salt; bring to a boil over medium heat. Simmer potatoes for 12 minutes, remove and place in an ice bath
3. Place a large skillet over medium-high heat
4. (Optional - rub tuna on all sides with olive oil.) Season tuna with a fair amount of salt and pepper
5. Lay the tuna in the hot pan and sear for approximately 45 seconds on each side; as the tuna cooks, the red meat will become whiter. Transfer to a paper towel to absorb some of the fat. Then transfer to a cutting board and slice

Assemble

1. To assemble the salad, lightly dress lettuce with vinaigrette and place on serving plate
2. Combine the potatoes, green beans, radish,olives and carrots in a large mixing bowl
3. Drizzle the vegetables with enough vinaigrette to fully moisten and toss gently to coat; season with salt and pepper. (Take care not to mush up the ingredients - the important thing about salad nicoise is that it is arranged nicely on a platter with all the elements keeping their individual integrity)
4. Place vegetables atop the lettuce and then lay slices of the seared tuna attractively across the top. Finish with capers, salt and pepper to taste, drizzle with vinaigrette and serve