Stir together 1/2 cup olive oil, 1 tablespoon parsley, and red pepper flakes. Toss tuna with marinade, and set aside to marinate for 30 minutes.

Pour vinegar, orange juice, lemon juice, lime juice, and soy sauce into the bowl of a blender. Add shallot, 1 tablespoon parsley, thyme, dill, honey, Dijon mustard, jalapeno, and ginger. Blend on high until smooth, then add 3/4 cups olive oil in a slow, steady stream with the blender running. Season to taste with salt and pepper, and set aside.

Bring a large pot of salted water to a boil over high heat. Fill another large container with half ice, half cold water, and set aside. Add the haricots verts to the boiling water, and cook until just tender, 35 to 40 seconds. Remove from the water, and immediately plunge into the ice water to cool. Next, blanch the carrots until just tender, about 1 1/2 minutes; chill in ice water until cold.

When the vegetables are cold, remove from the ice water and pat dry. Place into a large bowl, and toss with the halved tomatoes, olives, onion, and chervil; set aside.

Heat a heavy-bottomed skillet over high heat until very hot. Remove tuna steaks from marinade, and wipe off excess marinade. Season the tuna to taste with salt and pepper, then sear in hot skillet to desired doneness, about 1 minute per side for rare.

To assemble, toss the vegetable salad with enough dressing to lightly coat. Divide the salad among 4 plates, and place a seared tuna steak on top of each. Drizzle with additional dressing to serve.