Grate or miroplane the rinds of both lemons, and toss in a small bowl with two tablespoon of olive oil, and 1/2 teaspoons of salt, pepper and Herbs de Provence. Rub the mixture on both sides of each tuna steak.
Grill, or sear (in a non-stick skillet) the tuna, 3-4 minutes per each side. Be careful not to overcook- you want the steaks to be pink in the center and lightly browned on each side. Remove the steaks and let rest for 5 minutes.
In a large bowl, place the salad greens, sundried tomatoes, and chopped parsley.
In a small bowl, slice the lemons in half and squeeze the juice. Add the remaining 3 tablespoons of oil, and the rest of the salt and pepper. Whisk to blend completely. Pour half of the dressing over the salad and toss to coat completely.
Thinly slice the steaks on an angle, and arrange on top of the salad; drizzle the rest of the dressing over the tuna. Sprinkle with chopped scallions and serve up!