UPDATE 8/18/12: A while ago I saw in a recipe header in Dorie Greenspan's Around My French Table that the French eat their Nicoise salad with canned tuna.
The potato salad is amazing and I'll be making it as a stand alone item in the future.
Grilled Tuna Nicoise Platter
adapted from The Barefoot Contessa Cookbook by Ina Garten
8 (1-inch-thick) fresh tuna steaks (about 4 pounds)
Good olive oil
Freshly ground black pepper
3/4 pound French string beans (haricots verts), roasted (see method here)
1 recipe French Potato Salad, recipe follows
2 pounds ripe tomatoes, cut into wedges (6 small tomatoes)
8 hard-cooked eggs, peeled and cut in 1/2
1/2 pound good black olives, pitted
1 bunch watercress or arugula
For the vinaigrette:
3 tablespoons Champagne or sherry vinegar
1/2 teaspoon Dijon mustard
1/2 teaspoon kosher salt
1/4 teaspoon freshly ground black pepper
10 tablespoons good olive oil
To grill the tuna, get a charcoal or stove-top cast iron grill very hot. Brush the fish with olive oil, and sprinkle with salt and pepper. Grill each side for only 1 1/2 to 2 minutes. The center should be raw, like sushi, or the tuna will be tough and dry. Arrange the tuna, haricots verts, potato salad, tomatoes, eggs, olives, watercress, if used, on a large flat platter.
For the vinaigrette, combine the vinegar, mustard, salt, and pepper. Slowly whisk in the olive oil to make an emulsion. Drizzle some over the fish and vegetables and serve the rest in a pitcher on the side.
French Potato Salad:
1 pound small white boiling potatoes
1 pound small red boiling potatoes
2 tablespoons chicken stock
1/4 cup minced scallions (white and green parts)
2 tablespoons minced fresh dill
2 tablespoons minced flat-leaf parsley
2 tablespoons julienned fresh basil leaves
Drop the white and red potatoes into a large pot of boiling salted water and cook for 20 to 30 minutes, until they are just cooked through. Drain in a colander and place a towel over the potatoes to allow them to steam for 10 more minutes. As soon as you can handle them, cut in 1/2 (quarters if the potatoes are larger) and place in a medium bowl. Toss gently with the chicken stock. Allow the liquid to soak into the warm potatoes before proceeding.
Add a few tablespoons of the vinaigrette (above) to the potatoes. Add the scallions, dill, parsley, and basil. Serve warm or at room temperature.