3 star anise pods
1 3″ cinnamon stick
4 whole cloves
2 Tbsp. vegetable oil, plus more for noodles
2 medium onions, peeled, halved
1 2″ piece ginger, scrubbed, sliced lengthwise ¼” thick
3 lb. 2″–3″ sections mixed soup beef bones (oxtail, marrow, knuckles, and/or neck bone), rinsed under cold running water to remove blood and excess bits
1 lb. beef brisket or chuck, cut into 2″ pieces
2 Tbsp. (or more) fish sauce
½ oz. yellow rock sugar or 3 tsp. granulated sugar
2½ tsp. Diamond Crystal or 1¼ tsp. Morton kosher salt; plus more (optional)
10 oz. dried thin Banh Pho rice noodles
8 oz. beef eye of round, sirloin steak, London broil, or tri-tip steak
Set a 6-qt. Instant Pot to high sauté. Toast star anise, cinnamon stick, and cloves, stirring, until fragrant and crackling slightly, about 2 minutes. Add 2 Tbsp. oil and work around to coat bottom of pot. Reduce heat to medium, add onions, cut sides down, and ginger, and cook, undisturbed, until deep brown in spots, 5–7 minutes.
Pour in 1 cup water, scraping up any browned bits with a wooden spoon, then add beef bones, brisket, fish sauce, sugar, 2½ tsp. Diamond Crystal or 1¼ tsp. Morton kosher salt, and another 6 cups water (or just up to your max fill line). Lock lid and turn venting knob to sealing position. Cook on high pressure 1 hour (it will take about 20 minutes to come to pressure before the cook time begins). Naturally release pressure 30 minutes.
While the broth is cooking, place noodles in a large bowl and pour in cold water to cover. Let soak 30 minutes. Drain noodles and rinse to remove excess starch.
Freeze beef eye of round until firm, 20–30 minutes. Thinly slice against the grain, then chill in refrigerator until ready to serve.
Once pressure on pot has released 30 minutes, place a kitchen towel loosely over vent to prevent splattering. Using a wooden spoon, gradually open venting knob. As soon as floating pin drops, carefully open lid. Using tongs, transfer bones to a large bowl.
Place brisket in another large bowl and pour cool water over to cool down and keep from drying out. Using a fine-mesh sieve, scoop out solids from broth; discard aromatics and reserve any meat and bones for serving if desired. (Leftover meat and bones can also be reserved for another use; add to fried rice or bibimbap or scoop out marrow and slather it over slices of grilled toast.) Skim fat from surface with a ladle and discard. Taste broth and season with more fish sauce or salt if needed. Set to low sauté and simmer gently while you cook the noodles.
Fill a large pot one third of the way with water and bring to a rolling boil. Add noodles and cook, using chopsticks or a wooden spoon to stir, until just al dente, about 15 seconds. Drain noodles in a colander and rinse well under cold water to stop cooking. Drizzle a little oil over and toss to coat (this will keep them from sticking together).
Remove brisket from water and thinly against the grain. Divide noodles among deep bowls. (Pro tip: Before adding noodles, swirl hot water inside bowls to warm up, then discard.) Top each bowl with a few slices of brisket, sliced beef eye of round, and any reserved meat and bones (if using) and top with sliced onion, scallions, and cilantro (if using); season with pepper. Ladle hot broth over raw beef to cook.
Arrange Thai basil leaves, mint leaves, mung bean sprouts, chiles, and lime wedges on a platter for topping pho as desired and serve with Sriracha and hoisin sauce in small bowls for dipping.