Into a soup bag, toss in the star anise, cinnamon, bayleaf, Szechuan peppercorn, fennel seeds, coriander seeds, cumin seeds and black pepper. Set aside for later use.
In a pan, heat enough oil to sear beef until brown and set aside.
In the same pan, stir-fry preserved vegetables then set aside.
In a stockpot, heat some oil over medium-high heat. Add in onion, garlic, ginger, spicy bean paste, sa cha sauce and tomato paste.
Fry for about 3 minutes to combine all ingredients well.
Toss in previously fried preserved vegetables, dried chili, carrots and tomatoes.
Add in water, followed by spice bag and beef slices.
Cover and simmer over low heat for 2 hours.
Ladle the hot soup and beef chunks into noodle bowl and serve immediately. Garnish with spring onions.