Rinse turkey; pat dry. Make a pocket in each tenderloin by cutting lengthwise from one side almost to, but not through, the opposite side; set aside. In a bowl combine the spinach, cheese, and black pepper. Spoon spinach mixture into pockets. Tie 100 percent cotton kitchen string around each tenderloin in 3 or 4 places to hold in stuffing.
In small bowl combine oil, paprika, salt, and ground red pepper; brush evenly over tenderloins. Grill on the lightly greased rack of an uncovered grill directly over medium heat for 16 to 20 minutes or until turkey is tender and no longer pink in center of the thickest part; turn once. Remove and discard strings; slice tenderloins crosswise. Makes 4 servings.