1.Place the bones and beef shank in large stockpot and add water to cover. Bring to a boil and boil for 5 minutes. Rinse each one well and place the beef shank in the fridge.
2.Spray a large sheet pan covered with foil. Add bones, ginger, and 1 onion cut into wedges. Broil until slightly charred then set aside.
3.Meanwhile, add star anise, cloves, cinnamon stick, black cardamom, fennel seeds, and coriander seeds into the Instant Pot insert. Press saute button on high and saute for about 3 minutes, until fragrant then turn off. Pour into a spice bag and add it back into the pot.
4.Transfer the bones to your Instant Pot, along with the ginger and onions. Add 2 green onions cut into 4-inch pieces, fish sauce, rock sugar, and salt. Cover everything with 7 cups of water. Seal the Instant Pot and place on the manual high pressure setting for 120 minutes. Allow the pressure to release naturally, about 1 hour.
5.Open up the pot and add the beef shank then put it on the meat/stew setting for 30 minutes on high. Allow the pressure to release naturally, about 1 hour. Open the pot and skim the broth for excess fat and impurities.
6.Strain soup into another large pot. Keep the beef shank and discard the rest. Adjust seasoning by adding more salt, sugar, and/or fish sauce to taste. Bring soup to a boil in the pot.
7.To serve, boil the noodles according to package instructions. Rinse noodles with water then divide among bowls. Add to the bowls slices of beef and the beef shank. Slice onion and add on top, with 1 chopped green onion, and cilantro. Cover with broth, and serve with bean sprouts, Thai basil, limes, and jalapeno.