Heat a pot on medium high heat. Once hot, add the oil. Saute the mushrooms until golden brown and tender. Remove them from the pot and set them aside.
Lower the pot to medium heat, add in the broth, dashi, fish sauce, hoisin sauce, soy sauce, and scallions. Bring to a simmer to build deep flavor, about 20 minutes.
Add in the rice noodles and cook until tender. Refer to the instructions on the package for cooking time.
Portion the noodles into the bowl. Add in the sirloin and mushrooms, ladle the hot soup over top. The thinly sliced sirloin will cook when it comes in contact with the hot broth.
Top the pho with bean sprouts, mint, cilantro, and basil right before serving.