Boil angel hair pasta according to package directions for al dente.
While pasta is cooking, combine 2 tablespoons sesame oil, soy sauce, rice vinegar, tahini, peanut butter, sugar, ginger, garlic, and sriracha together in a separate bowl, whisking thoroughly.
Drain the pasta and toss with 1 teaspoon of sesame oil. Pour sauce over noodles and toss to combine. Divide among four bowls and garnish with green onion and sesame seeds.
The sauce can be made in advance so that all you need to do is boil some noodles to have an easy and delicious lunch!