Preheat oven to 350 degrees. Grease a 9 x 13 baking dish.
Prepare manicotti shells according to package instructions. Drain and set aside.
In a skillet, brown ground turkey until no longer pink. Stir in crushed tomatoes, dried spices and tomato paste. Mix to fully combine. Cook an additional 5 minutes, then, remove from heat.
Spread half of the sauce mixture into the bottom of the prepared baking dish.
Stuff each cooked manicotti shell with a piece of string cheese. Then, place in baking dish, on top of sauce.
Top stuffed manicotti shells with remaining sauce mixture.
Cover and bake for 25 minutes. Remove cover and sprinkle top with shredded mozzarella cheese. Bake an additional five minutes or until melted.