Chinese Braised Beef Shank

1 beef shank (around 1500g, bone removed)
2L beef stock
20ml (4 tbsp.)dark soy sauce
20ml (4 tbsp.) light soy sauce
2 leek onions
2 green onions
1 thumb ginger
2 shallots
1/3 cup shaoxing wine
20g rock sugar

Spices (around 30g in totally, wrapped in a spice bag)
4 star anises
2 small piece of Chinese cinnamon
4-6 bay leaves
1/2 teaspoon Sichuan peppercorn
4 cloves
1/2 teaspoon whole cumin seeds
1/2 teaspoon fennel seeds
1 cardamom
3 Amomum Cardamomum pods
1 Amomum tsaoko
2-3 dried chili peppers (optional)