Rinse bones well many times. Fully soak them in cold water & refrigerate overnight to remove blood and impurities from bones
Parboil bones with salt. Once it's boiled, cook for 5 mins and take out. Rinse well under water until cleaned
Char onions & ginger until fragrant (or air fry 380F-190C for 8 mins). Arrange bones + charred onions + gingers in the pot. Add salt, peppercorn, and water to the max level. Pressure cook 45 mins, then Natural release 45 mins
Filter to get the broth. Discard onions & ginger (optional). Utilize bones again + add beef brisket & beef tendon + add sugar & seasoning to make the meat savory. Pressure cook 15-20 mins, then Natural release 10 mins
Roast Pho spice until fragrant. Add to the spice ball/tea bag/cheesecloth
Take out beef brisket and tendon. Add Pho spices to the pot. Saute on Low for 20-30 mins. Season again to your liking with salt, fish sauce, and sugar
Assemble: add Pho noodles, add toppings beef brisket/tendon/raw slices, and top with the boiling broth. Finish with chopped scallions and onion slices
Enjoy when it's hot with basil, cilantro, bean sprouts, sriracha, and Hoisin sauce