Stuffed Eggplant with Lamb and Pine Nuts

Name: Stuffed Eggplant with Lamb and Pine Nuts
Ingredients: Four 1-pound eggplants, halved lengthwise; 1 tablespoon extra-virgin olive oil, plus more for brushing; Salt; Freshly ground pepper; 1 tablespoon ground cinnamon; 1 1/2 teaspoons ground cumin; 1 1/2 teaspoons sweet paprika; 1 large onion, finely chopped; 1 pound ground lamb; 3 tablespoons pine nuts; 2 teaspoons tomato paste; 1/4 cup chopped parsley; 1 tablespoon sugar; 1 tablespoon fresh lemon juice; 1 teaspoon tamarind concentrate; One 1 1/2-inch cinnamon stick