Ingredients

TUNA AND EGGPLANT

1. 2 large tomatoes, cut into 1/2 -inch dice
2. 1 medium seedless cucumber, peeled and cut into 1/2 -inch dice
3. 18 Calamata olives (about 3 1/2 ounces), pitted and coarsely chopped
4. 1 tablespoon minced red onion
5. 2 tablespoons fresh lemon juice
6. 1 tablespoon extra-virgin olive oil plus about 1/4 cup for brushing
7. 1 medium eggplant, peeled and sliced crosswise 1/4 inch thick
8. Salt and freshly ground pepper
9. Six 3-ounce tuna steaks, about 1/2-inch thick
10. Tahini Sauce (recipe follows)
11. 1 tablespoon coarsely chopped chives

TAHINI SAUCE

1. 1/3 cup plus 2 tablespoons tahini (see Note)
2. 1 small garlic clove, minced
3. 2 tablespoons fresh lemon juice
4. Salt and freshly ground pepper

Directions

1. In a bowl, combine the tomatoes, cucumber, olives, onion, lemon juice and the 1 tablespoon olive oil.
2. Heat a grill pan or preheat the broiler. Brush the eggplant slices with some of the olive oil and season with salt and pepper. Working in batches, grill the eggplant over moderate heat, or broil until very tender and browned, about 2 minutes per side. Transfer the eggplant to a plate and keep warm. 
3. Wipe out the grill pan. Brush the tuna on both sides with olive oil and season well with salt and pepper, pressing the seasoning into the fish. Grill the tuna in the pan over high heat, or broil until nicely browned, about 2 minutes per side. 
4. Make the Tahini Sauce: In a food processor, combine the tahini, garlic, and 1/2 cup of water and pulse once or twice to blend. Add the lemon juice, salt and pepper and pulse just until combined. It's important not to overprocess the sauce, or it will be too thick; it should be the consistency of heavy cream. 
5. Make a pool of the Tahini Sauce on each of 6 plates and fan the eggplant slices out on it. Season the tomato salad with salt and pepper and spoon it on top of the eggplant. Set the tuna on the salad and garnish with the chives. 

Make Ahead

The salad can stand at room temperature for 4 hours.

Notes

Be sure to stir the tahini (Middle Eastern sesame seed paste) to combine the oil and the paste before measuring it.