Combine water, chicken broth, garlic, soy sauce, brown sugar, oyster sauce, sesame oil, and chili paste in the Instant Pot. Whisk to fully incorporate.
Place broken spaghetti noodles on top, making sure they are spread out in the pot and covered by the liquid.
Cover the Instant Pot and cook on High pressure for 6 minutes. Once timer goes off, do a quick release.
Once all pressure is released, open the pot and stir the pasta noodles, allowing the noodles to separate and the sauce to thicken.
Serve and top with sesame seeds and green onions if desired. Enjoy :)