Baba Ghanouj on Pita

Name: Baba Ghanouj on Pita
Ingredients: 2 large eggplants (about 2 pounds each), peeled and cut into 1-inch cubes; 3 tablespoons olive oil; 3/4 teaspoon salt; 1/2 teaspoon fresh-ground black pepper; 8 pitas; 1/4 cup lemon juice (from about 1 lemon); 1/3 cup tahini; 3/4 teaspoon ground cumin; 2 cloves garlic, peeled; 1 small head romaine lettuce (about 3/4 pound), cut crosswise into 1-inch strips (about 5 cups); 1 plum tomato, halved lengthwise and cut crosswise into thin strips; 1 cucumber, peeled, halved lengthwise, seeded, and sliced thin; 1/2 teaspoon wine vinegar