Cook the pasta in salted water, about 8-9 minutes for al dente. Drain, cool, toss with 1/2 TBS sesame oil and set aside.
In a small mixing bowl, add sriracha, soy sauce, minced garlic, ginger, red pepper flakes, oyster sauce and 1 TBS of the sesame oil. Whisk and set aside.
Heat a skillet to medium high with 1 TBS sesame oil. Add shrimp, and 1 TBS of the sauce and cook for 4-5 minutes or until shrimp are pink and cooked. Remove from pan and set aside.
Add remaining sesame oil to skillet, then add zucchini. Cook for 2 minutes, then add mushrooms and red bell pepper. Continue to cook for 3-4 minutes or until peppers are slightly softened and mushrooms are cooked. Add cooked spaghetti, green onions and remaining sauce.
continue to cook for 2-3 minutes, or until noodles are hot. Place shrimp back in and toss until warm. Pour into serving bowl, sprinkle with sesame seeds and cilantro. Serve.