Prepare aromatics and vegetables: Slice the onion, garlic, ginger, and chili peppers. Chop the scallions, separating the white and green parts. Dice the tomatoes, carrots, and slice the shiitake mushrooms.

Slice and season beef: Slice beef into slightly thicker than ½ inch (1.3 cm) slices. Season with ¼ tsp each of salt and pepper.

Prepare braising liquid: In a cup or bowl (at least 600 ml capacity), combine beef stock, water, soy sauce, michu, salt, five spice powder, and sugar. Stir well to dissolve the sugar.

Heat a large sauté pan over medium heat until hot. Add avocado oil.

Increase heat to medium-high and sear beef for 2 minutes on one side, then 1 minute on the other. Remove and set aside.

In the same pan, sauté onion, garlic, ginger, chili peppers, and white scallion parts over medium-high heat for 3 minutes.

Add tomatoes and doubanjiang. Sauté for 2 minutes, then turn off the heat.

Transfer sautéed aromatics, tomatoes, and beef into the Instant Pot.

Add carrots, shiitake mushrooms, cinnamon stick, bay leaf, and star anise (if using).

Stir the braising liquid again and pour it into the pot. Use a wooden spoon to distribute evenly.

Seal the Instant Pot lid and pressure valve. Set to Manual - High Pressure - 40 minutes.

Once done, allow a natural release for 15 minutes, then carefully turn the valve to quick release.

In a separate pot, blanch vegetables for a few seconds and set aside.

Use the same water to boil noodles according to package instructions. Time this step so the noodles are ready to serve alongside the beef.

Taste the soup after cooking. It will be quite concentrated. Dilute with 1.5 to 2.5 cups (360-600 ml) of hot water if needed to lighten the flavor.

Divide noodles into individual bowls. Ladle beef, broth, and vegetables over the noodles. Garnish with cilantro and serve with pickled mustard greens if desired. Serve hot.