Set your SAUTE setting to HIGH. Heat your oil and add your onion, ginger and garlic for 4-5 minutes, stirring frequently until browned.
Stir in your star anise, cardamon pod(s), cinnamon, coriander and peppercorns until fragrant.
Pour in broth, fish sauce, brown sugar, lime juice, ½ tsp salt and water. Stir together. Place the lid on the instant pot and press CANCEL, to cancel the saute option. Then make sure the lid is locked and the vent is sealed shut. Press the PRESSURE COOKER option set on HIGH for 15 minutes. It will take about 15 minutes for it to come to pressure to start the 15 minute timer. Once the timer goes off, use the QUICK RELEASE.
While the instant pot is cooking, prepare your rice noodles according to the package.
Place a large bowl on the counter, and then take a mesh strainer and line it with the cheese cloth. Using a ladle, pour the broth into the mesh lined strainer and allow it to catch all of the seasonings, onion, ginger and cinnamon. Once the broth is strained, pour it back into the instant pot and turn your SAUTE setting back on HIGH.