Place beef in a pot and fill with 1 ½ Liter of water. Bring to a boil. Lower heat to low and cover the pot with lid. Let it cook for an hour or until meat is tender. Remove meat from the broth and transfer to a plate. The broth will also be used later.
Place ramen noodles in a big bowl. Pour boiling water making sure it is fully submerged. Let it stand for 5 minutes or until the ramen is cooked. Drain water and set aside.
In a pot, heat oil over high heat. Once the oil is hot, sear the beef for 1 minute each side. Remove from oil and transfer to a chopping board, cut into thin slices when ready to use.
In the same pot with oil over medium heat, add the garlic, white part of the green onions and carrots and cook for 3-5 minutes or until garlic and green onions are limp.
Add hoisin sauce, sriracha sauce, and soy sauce. Add a liter of the beef broth and beef broth cube. Bring to a boil and season with salt if needed and then cook until carrots are tender.
To assemble, divide noodles into 2 big bowls. Arrange slices of beef on top then add the Pak choi and bean sprouts. Pour in the soup (and carrots) then garnish with the green onions.