In large bowl, toss spaghettini with remaining ingredients except chopped peanuts. Cover and refrigerate. sprinkle each serving with 2 tablespoons peanuts.
To make Peanut Dressing: In bowl, whisk peanut butter with soy sauce. Add chili sauce, vinegar, sugar, chili-garlic sauce, sesame oil and garlic. Whisk to blend thoroughly. Gradually whisk in vegetable oil until mixture is emulsified. Cover and refrigerate. (Makes about 12 cups.)