Preparation / Directions:
Make the dressing: In a blender blend together the garlic, the vinegar, 1 tablespoon of the lemon juice, the sun-dried tomatoes, the plum tomatoes, and 1/4 cup water until the mixture is smooth and with the motor running add the oil in a stream.
Add the sour cream, the coriander, the additional lemon juice, and salt and pepper to taste and blend the dressing until it is combined well. (The dressing may be made 1 day in advance and kept covered and chilled. Let the dressing return to room temperature.)
In a large bowl toss the mesclun with the tomatoes and the corn and divide
the mixture among 4 plates. Brush the tuna on both sides with the oil, season it with salt and pepper, and grill it on an oiled rack set about 4 inches over glowing coals for 4 to 5 minutes on each side for medium-rare,
or until is cooked to the desired degree. Let the tuna stand for 3 minutes and cut it against the grain into 1/4-inch-thick slices. Divide the tuna slices among the salads and pour about 1/4 cup of the dressing over each serving. Serve any remaining dressing separately and garnish the salads with nasturtium blossoms.