Roasted Eggplant Sabich Sandwiches

Name: Roasted Eggplant Sabich Sandwiches
Ingredients: 2 tablespoons za’atar; 3 garlic cloves, finely grated, divided; ½ cup plus 2 tablespoons olive oil, divided; 1 large or 2 medium Italian eggplants (about 20 ounces), cut into ¾-inch-thick rounds; Kosher salt; ½ cup parsley leaves with tender stems; ½ cup plus 2 tablespoons chopped chives, divided; ½ cup tahini; 2 Persian cucumbers, quartered, cut into ½-inch pieces; 1 pint cherry tomatoes, halved; ¼ cup chopped mint; 2 tablespoons fresh lemon juice; 1 cup prepared hummus; 3 tablespoons (or more) harissa; ½ teaspoon ground cumin; Toasted pita, thinly shredded cabbage, quartered hard- or soft-boiled eggs, and Israeli pickles (for serving)