1 In a bowl, toss the mesclun with the chervil, basil, tarragon, and mint. Set aside.

2 Trim off and discard the dark blood section of the tuna. Sprinkle one side of each tuna steak with a teaspoon of thyme, a pinch of salt, and a pinch of pepper. Drizzle 1 tablespoon of olive oil over each steak and rub it into the tuna. Turn the steaks over and repeat on the other side.

3 Heat two 10-inch nonstick skillets over high heat until just smoking. Add 1 tuna steak to each skillet and sear until the tuna is browned on the outside and rare, but warm in the center, about 1½ minutes per side. Cut the tuna on the diagonal into ½-inch-wide slices.

4 Toss the mesclun mixture with the vinaigrette. Divide the salad among 4 dinner plates, mounding it to the side of the plate. Fan the tuna slices in a half-circle around the salad. Drizzle 1 tablespoon of olive oil on each plate, making an arc in front of the tuna. Drizzle a few drops of balsamic vinegar into the olive oil and serve immediately.