Place the chicken carcass, legs and wings in a medium-large saucepan, as well as the halved onion (no need to peel it), sliced ginger, cinnamon and star anise.
Pop the pan over medium heat and bring to a simmer. Cook, skimming off any foam from the surface if necessary, for 20–25 minutes (use this time to cook your noodles and prepare the other ingredients you’ll serve your leftover chicken pho with).
Add the soy, fish sauce and sugar. Taste the broth, and add more salt or fish sauce to your liking.
Place a fine sieve over a large bowl and carefully strain the pho broth, discarding the aromatics.
Add cooked rice noodles to serving bowls, and top with shredded chicken and spring onion. Ladle over the hot soup. Serve with bean shoots, lime wedges, Thai basil and red chilli on the side, plus hoisin and sriracha sauces.
