Blanch beef to rid the scum: Into a large pot, place beef cubes, ginger slices and 10 cups of cold water. Bring to a rolling boil. Boil for 5 minutes until the scum floats to the top. Place a colander in the sink drain. Give the beef a quick rinse. Discard ginger slices. Drain well.

Toast spices and make sachet: Lay out a 5” square piece of cheesecloth. Set a pot over medium heat. Toast star anise, bay leaves, coriander seeds and cinnamon stick in the dry pot briefly until fragrant and darkened slightly, ensuring not to burn them. Set cinnamon stick aside. Scoop star anise, coriander seeds and bay leaves onto cheesecloth and tie with twine.

Make soup base: Increase heat to medium-high. Add 2 tbsp of oil and add tomatoes, onion, garlic, ginger, white parts of scallion and dried chili peppers if using. Season with salt and sauté until tomatoes and onions are softened, about 3 minutes. Add doubanjiang, tomato paste and sugar.

Add the drained beef. Add beef into pot. Stir well and cook a couple of minutes.

Add the spice sachet and remaining ingredients: Add spice sachet, cinnamon stick, Shaoxing wine, soy sauce, dark soy sauce and water. Bring to a boil and reduce to a simmer for 5 minutes. Skim and discard the scum. Cover, ensuring liquid is at a gentle simmer rather than a vigorous boil. Braise 2 hours or until beef is fork-tender.

Cook noodles and leafy greens: Bring a large pot of water to a boil. Cook noodles and leafy greens at the same time. Drain, set bok choy aside and rinse noodles under cold water to rid excess starch. Divide noodles and bok choy among serving bowls.

Serve: Bring beef and broth to a strong simmer to ensure everything is piping hot. Taste broth and adjust seasoning if needed. Ladle beef and broth over the noodles and leafy greens. Serve immediately with reserved scallions, chili oil and/or pickled mustard greens.