Eggplant's meaty texture is a delicious vegetarian stand-in for the lamb that typically fills a gyro sandwich. The vegetable absorbs the lemony-herby-spicy marinade like a sponge, so if you have time, let it marinate for the full day.
To prepare eggplant: Trim ends off eggplant and cut lengthwise into 1/8-inch-thick slices. Place in a colander and toss with 1 teaspoon salt. Let stand for 30 minutes. Rinse and pat dry. Transfer the eggplant to a 9-by-13-inch baking dish.
Meanwhile, whisk oil, 2 tablespoons dill, lemon juice, garlic, coriander, cumin, oregano and piment d'Espelette (or Aleppo) in a small bowl. Rub the marinade on the eggplant. Refrigerate for at least 3 hours and up to 1 day.
To prepare tzatziki: Place cucumber on a clean kitchen towel, gather it up and squeeze out as much liquid as possible. Place the cucumber in a small bowl and mix in yogurt, dill, garlic, salt and pepper. Refrigerate until ready to use.
To grill & serve: Preheat grill to medium-high. Grill the eggplant, turning once, until lightly charred, 3 to 5 minutes per side. Serve in pitas with tomato, lettuce, onion and some of the tzatziki.
To make ahead: Marinate eggplant (Steps 1-2) for up to 1 day.
2 1/2 starch, 3 vegetable, 5 1/2 fat