In a 5- to 6-quart pan over medium-high heat, stir sesame seed until lightly toasted, 6 to 8 minutes. Pour into a small bowl and set aside.
Add oil and ground turkey to pan; stir over high heat until meat is crumbled and lightly browned, about 5 minutes.
Mix pickles and peanut sauce with meat; add broth and cover pan. When mixture is boiling, uncover, add fettuccine, and stir to separate pasta; when boil resumes, reduce heat and simmer until pasta is tender to bite, about 3 minutes total.
Stir in chopped green onions. Ladle soup into bowls; sprinkle with sesame seed, peanuts, and green onion slivers. Eat with chopsticks or a fork and spoon.
Peanut sauce: In a bowl, stir to blend 3 tablespoons each peanut butter, soy sauce, Asian (toasted) sesame oil, and sugar; 2 tablespoons rice vinegar; and 1 teaspoon (or to taste) hot chili flakes.