Make the Filling:

1. Prepare the glutinous rice. Soak glutinous rice in water for 3+ hours or overnight. Drain water and let it sit for 10 minutes. Transfer the rice to a bowl and add 1/2 cup of soy sauce and dark soy sauce. Stir until the soy sauce is fully immersed in the rice and the rice is fully coated. 
2. Prepare the pork belly. In a large bowl, combine pork belly, 1/2 cup soy sauce, cooking wine, ginger, sugar, salt and white pepper powder. Add in peanut and chestnuts (optional). Toss to combine. Cover the bowl with plastic wrap and place in the refrigerator to marinate for at least 2 hours.
3. Prepare the shiitake mushrooms. In another bowl, soak shiitake mushrooms in warm water for 1 hour. (They will float at first, but will eventually sink to the bottom of the bowl).
4. Prepare the reed leaves. Add reed leaves in a pot and add a few cups of water. Bring to a boil over high heat and cook for 20 minutes. This will make the leaves softer and easier for wrapping. Leave it soaked in the pot until it cools down and you are ready to wrap, or rinse it under cold water. Make sure the leaves are damp when you are ready to wrap, for easier handling.

Assemble and Cook:

1. Overlap 2-3 pieces of bamboo leaves and twist turn to form a narrow cone. (Using 3 leaves per tamale makes it easier for wrapping if you are a beginner). 
2. Add a layer of glutinous rice to fill 1/3 of the space in the cone. Add 1 piece of pork belly, a couple peanuts, 1 chestnut, and some mushrooms to fill another 1/3 of the cone. Top up remaining 1/3 of the space with more rice and make it level on the top.
3. Fold the two sides of the leaf over the rice. Then, fold the top of the leaf down to cover the rice completely. Tie with a cooking string to seal everything inside. Repeat to make 5 more zongzi tamales.
4. Place zongzi tamales in a pot. Fill the pot with water to completely cover the zongzi tamales by over 1-inch. Bring the water to a boil over high heat, then turn the heat down to low, cover and simmer for 1 hour. Check on them periodically to make sure that they are completely submerged in water the whole time. If needed, add more water. 
5. Remove from heat and leave in the pot of water until ready to serve. If you take them out before you are ready to eat, they will dry out. To reheat, simply boil again in water for 10 minutes.