How to Make It
Select SAUTÉ setting on a 6-quart multi-function programmable pressure cooker (such as Instant Pot). Allow to preheat about 5 minutes. Place onion halves, cut side down, in cooker. Add ginger; cook, undisturbed, until onion is slightly charred on cut sides, about 10 minutes. Add coriander seeds, cloves, and star anise; cook, stirring constantly, until fragrant, about 1 minute. Add chicken, broth, fish sauce, and brown sugar.
Close and seal lid. Turn Pressure Release Valve to Sealing position. Select MANUAL/PRESSURE COOK setting. Set to HIGH PRESSURE for 15 minutes. (It will take 15 to 20 minutes for cooker to come up to pressure before cooking time begins.) Let pressure release naturally. (This will take about 10 minutes.) Carefully turn Pressure Release Valve to Venting position, and let steam fully escape. (This will take 1 to 2 minutes.) Carefully remove lid.
Transfer chicken to a large plate; let rest until cool enough to handle, about 10 minutes. Remove and discard skin and bones; shred meat.
While chicken cools, pour broth mixture in cooker through a fine mesh strainer into a heatproof bowl; discard solids. Return strained broth to cooker. Add noodles, stirring to submerge; let stand until softened, about 5 minutes.
Return shredded chicken to mixture in cooker. Ladle soup evenly into 8 bowls. Top evenly with bean sprouts, cilantro, chiles, and other desired toppings. Serve with lime wedges.