For the broth:
1 large onion, peeled and halved
2 3-inch pieces of fresh ginger, halved
5 star anise
4 whole cloves
3 cinnamon sticks
2 teaspoons ground coriander
Pinch of ground cardamom
2 (32 oz each) cartons beef stock
1 tablespoon brown sugar
2 teaspoons fish sauce
Salt, to taste
For the soup:
8 oz raw steak, very thinly sliced (such as sirloin, round eye, flank steak, chuck roast, brisket, or london broil)
8 oz thin rice noodles, uncooked
Fresh Thai basil leaves
Thai bird chiles or jalapeños, thinly sliced
Green onions, thinly sliced
Turn oven to broil on high. Brush onion halves and ginger with olive oil and place on a sheet pan. Place pan about 8 inches under broiler element until onion and ginger are slightly charred, 5-10 minutes.
Meanwhile, place a large stockpot over medium-high heat. Add cloves, cinnamon sticks, coriander, and cardamom and toast for 3-4 minutes until fragrant. Be careful not to burn.
Add the charred onion and ginger, followed by the beef stock and bring to a boil. Reduce heat to medium-low, cover, and simmer at least 30 minutes.
While broth simmers, prepare noodles according to package instructions. Drain and rinse with cold water to halt further cooking. Toss with a drizzle of sesame oil to prevent sticking.
Strain the broth, discarding the onion, ginger and spices. Return broth to pot, then add fish sauce and brown sugar. Season to taste with salt. Bring back to a low simmer so broth is hot enough to cook beef.
Serve by adding a handful of noodles and a portion of sliced raw meat to individual bowls. Ladle the simmering-hot broth into bowls, making sure to completely submerge steak in order for it to properly cook. Top bowl with garnishes of choice. Stir garnishes into bowl to add flavor, serve immediately and enjoy!