In a frying pan over medium heat, toast the cinnamon, star anise, cloves, coriander, fennel and cardamom until fragrant, stirring frequently and being careful not to burn. Add to the crock pot. This step is really important!!! It allows the flavour of the spice to really come through. No oil is needed to toast these.
In the same pan, add the ginger and onion with the cut sides down and cook until they start to become charred, about 10 minutes. Add to the crock pot.
Boil your oxtail if using in a separate pot of water for 10 mins. This boils out any impurities and will give your broth a nice clear appearance. Remove the Oxtail from the water and rinse with fresh water, then add them to the crock pot.
Add chicken breasts to the crock pot. Pour in beef stock and an additional one cup of water. Add the soy sauce, fish sauce and sugar.
Cook on low for 8 hours or high for 5 hours if using a crock pot. Simmer on low for 5 hours if using a stock pot.
When done, remove meat and set aside. Strain the broth through a fine mesh strainer to remove the solids.
Remove the meat from the bone and add the meat back to the broth. Taste the broth and add salt or more fish sauce if needed.
Steam your broccoli, some bok choy, and sliced carrots on the side and then add them to the stock OR add the veggies and let the stock simmer for another 20 mins until your veggies are soft. I wait to add my veggies until the last 20 mins or I steam them separately as I don’t like it when they are too soft.
Cook the rice noodles according to package instructions, set aside.
To prepare each bowl of soup, add a serving of rice noodles to the bowl and add slices of the sirloin steak. Pour the hot broth over the noodles and meat, which will cook the steak slices (if you don’t want to do this, just add the steak slices to the hot broth a few minutes before serving to cook it.
Serve with the additional toppings and allow each person to garnish the soup as they wish.