Eat For Eight Bucks: Cold Sesame Noodles

Name: Eat For Eight Bucks: Cold Sesame Noodles
Ingredients: 1 pound Chinese egg noodles (or spaghetti or linguine); 1/2 teaspoon toasted sesame oil; 6 tablespoons tahini; 3/4 cup water, plus more if needed; 1 tablespoon rice vinegar or white vinegar; 3 tablespoons soy sauce; 1 1/2 teapoons sugar; 2 garlic cloves, minced; 1 scallion (both white and green parts), thinly sliced; 1 1/2 inches fresh ginger, peeled and chopped (1 tablespoon); Chinese chili oil (optional); Sesame seeds (optional)