Rinse the beef brisket and sirloin, then soak them in cold water for about 30 minutes to tenderize.

Place the thinly sliced beef for rare topping in a separate bowl. Marinate with ginger, garlic, black pepper, and fish sauce. Mix well and refrigerate to let the flavors absorb.

Bring a small pot of water to a boil. Blanch the beef bones, then discard the water to remove any odor. Rinse the bones thoroughly.

In a large pot over high heat, add the soaked beef and beef bones. Cover with water and bring to a boil. Season with fish sauce and salt to taste.

When the broth comes to a boil and gray foam rises to the surface, skim off all the foam with a strainer or spoon. The more thoroughly you skim, the clearer and more appealing the broth will be.

Cover the pot, reduce the heat to low, and simmer the beef for about 4 hours.

Char the ginger, onion, star anise, cinnamon stick, and black cardamom over an open flame for about 3 minutes until fragrant. Add them to the pho pot. If you want to keep the broth clear, wrap the spices in a small cloth bag before adding.

After 2 hours, check the beef with chopsticks to see if it's tender and cooked through. Remove the beef and let it cool on a plate for about 10 minutes.

Pick and wash the herbs and green onions, then finely chop.

Reserve the white parts of the green onions, cut into 2-inch (5 cm) lengths, and slice into quarters. Thinly slice the onion and briefly blanch in the pho broth.

Bring a clean pot of water to a boil to blanch the pho noodles. Blanch each portion of noodles separately, then place into individual serving bowls.

Slice the cooked brisket and sirloin into thin, large pieces about 1.5 x 2 inches (4 x 5 cm), and arrange on top of the noodles in each bowl.

Take the marinated rare beef from the refrigerator and layer it on top of the noodles.

Add the chopped green onions, cilantro, blanched onion slices, and green onion tops to each bowl.

Ladle the hot broth over the bowls, making sure the rare beef cooks gently. Before eating, squeeze lime, sprinkle black pepper, and add chili sauce to taste.