PreparationFor the dressing: Prepare a grill for medium heat; oil grate. Grill scallions and jalapeño, turning once, until lightly blistered and crisp-tender, about 2 minutes for scallions and 4 minutes for jalapeño. Transfer to a cutting board and let cool slightly. Slice open jalapeño and scrape out seeds (unless you like things very spicy); discard. Coarsely chop chile and scallions. Mix in a medium bowl with olives, pistachios, lemon juice, vinegar, and 5 Tbsp. oil; season dressing with salt and pepper. Dressing can be made 1 day ahead. Cover and chill. Bring to room temperature before serving. Assemble the salad: Mix thyme, sesame seeds, and garlic powder in a small bowl. Lightly coat pitas and eggplants with 2 Tbsp. oil; season with salt and rub with thyme mixture. Grill, turning occasionally and moving to a cooler part of grill if needed to avoid scorching, until pitas are golden and crisp and eggplants are browned and tender, 5 minutes for pitas, and 8–10 minutes for eggplants. Transfer to a platter and let cool slightly. Meanwhile, grill Halloumi until charred and soft, about 2 minutes per side. Transfer to platter with pitas and eggplants. Tear pitas and Halloumi into chunky pieces, then cut eggplants into bite-size pieces. Transfer to a large bowl and add cucumbers, tomatoes, and dressing. Give everything a good toss to bring it all together; season with salt. Top with mint leaves and dill sprigs. Cook's Note:Halloumi cheese can be found in Greek markets, natural foods and specialty foods stores, and some supermarkets.