Put in a pressure cooker 4 liters of water, add washed oxtail meat, add 1/2 cup of fish sauce, 1 teaspoon of salt, 2 small lumps of rock sugar, add roasted onions and ginger. Bring the water to a boil and cook for another 15 minutes, then take out the onions and stop, then add the roasted spices and cook for 8 minutes and then take them out. Adjust seasoning to suit your taste.
Pour pho into a bowl, add oxtail, pho broth, cilantro, onions,….