Step 1

Preheat the oven to 425 degrees F.

Step 2

Place the beef bones on a baking sheet and roast until browned, about 1 hour.

Step 3

At the same time, place the onion halves on a second baking sheet and roast until blackened and soft, about 45 minutes.

Step 4

Transfer the beef bones and the onion halves to a large stockpot.

Step 5

Add the ginger, the salt, the star anise, the fish sauce, and 4 quarts of the water to the beef bone mixture and bring to a boil.

Step 6

Reduce the heat to low and simmer the broth mixture, about 6-10 hours.

Step 7

Strain the broth into a saucepan and set aside.

Step 8

Place the rice noodles in a large bowl of water and let soak for 1 hour, then drain.

Step 9

After the noodles are done soaking, bring a large pot of water to a boil; cook the noodles in the boiling water for 1 minute, then drain.

Step 10

While you're waiting for the water to come to a boil, bring the broth to a simmer until heated.

Step 11

Divide the cooked noodles among four bowls and top them with the sirloin, the cilantro, and the green onion.

Step 12

Ladle the hot broth over the top of the meat.

Step 13

Stir and let sit until the beef is partially cooked and no longer pink, 1-2 minutes.

Step 14

Serve the pho with the bean sprouts, the Thai basil, the lime wedges, the hoisin sauce, and the chile-garlic sauce.