To prepare turkey, place first 3 ingredients in a small skillet, and cook over medium-low heat 2 minutes or until toasted and fragrant, shaking pan frequently. Place peppercorn mixture in a spice or coffee grinder; process until finely ground. Place mixture in a small bowl. Stir in 1 tablespoon oil, cinnamon, 1 teaspoon salt, and nutmeg to form a paste.
Remove and discard giblets and neck from turkey. Rinse turkey with cold water; pat dry. Trim excess fat. Starting at neck cavity, loosen skin from breast and drumsticks by inserting fingers, gently pushing between skin and meat. Rub spice paste under loosened skin, and rub over breast and drumsticks. Lift wing tips up and over back; tuck under turkey.
Place turkey, breast side down, on the rack of a broiler pan or roasting pan coated with cooking spray. Pour 2 cans broth into shallow roasting pan; place rack in pan. Bake at 400° for 45 minutes. Carefully turn turkey over (breast side up); bake turkey an additional 1 hour and 15 minutes or until a thermometer inserted in thigh registers 180°. Let stand 10 minutes.
To prepare gravy, place a heavy-duty zip-top plastic bag inside a 2-cup glass measure. Pour pan drippings into bag; let stand 10 minutes (fat will rise to the top). Seal bag; carefully snip off 1 bottom corner of bag. Drain drippings into a medium saucepan, stopping before fat layer reaches opening; discard fat. Bring to a boil. Reduce heat; simmer 5 minutes. Combine 1/3 cup water and cornstarch, stirring with a whisk. Stir the cornstarch mixture into pan; bring to a boil. Reduce heat; simmer 3 minutes or until slightly thick.
Place coriander, caraway, and cumin in a small skillet; cook over medium-low heat 2 minutes or until toasted and fragrant, shaking pan frequently. Place the mixture in a spice or coffee grinder; process until finely ground. Add crushed red pepper, jalapeños, and 2 garlic cloves; process until a paste forms. Remove spice paste from grinder; combine spice paste and yogurt. Add yogurt mixture to broth mixture; simmer 3 minutes. Stir in 1/2 teaspoon salt and 1/4 teaspoon black pepper.
To prepare couscous, heat 1 tablespoon oil in a large nonstick saucepan over medium-high heat. Add 8 garlic cloves; sauté 1 minute. Add 1 cup water and 2 cans broth to pan; bring to a boil. Stir in couscous and currants. Cover, remove from heat, and let stand 8 minutes. Fluff with a fork. Stir in parsley, cilantro, 1/2 teaspoon salt, and 1/4 teaspoon black pepper. Serve turkey with couscous and gravy. Discard skin before serving.
Note: Insert long-handled tongs or a heavy spatula into the cavity to support the weight of the turkey, and use another set of tongs or spatula to turn the bird.