Season the tuna with 1 tsp. salt and 1/4 tsp. pepper. Heat the oil in a 12-inch skillet over medium-high heat. Arrange the tuna in the skillet in a single layer and cook, turning once, until done to your liking (3 to 4 minutes for medium rare). Transfer the tuna to a large plate.
Reduce the heat to medium and add the shallot to the skillet. Cook, stirring, until golden-brown, about 1 minute. Add the tomatoes, olives, basil, 1/2 tsp. salt, and a few grinds of pepper; cook until warmed through and the tomatoes are just softened, about 2 minutes more. Remove the skillet from the heat and gently stir in the lemon juice.
Transfer the tuna to plates, top with the tomato salad, and serve.
Recipe courtesy of Fine Cooking.
nutrition information (per serving):
Calories (kcal): 300; Fat (g): 16; Fat Calories (kcal): 140; Saturated Fat (g): 3; Protein (g): 34; Monounsaturated Fat (g): 8; Carbohydrates (g): 4; Polyunsaturated Fat (g): 3; Sodium (mg): 650; Cholesterol (mg): 55; Fiber (g): 1.