Soak the rice overnight, or at least 3 hours to soften the rice. Drain and add oil and 1 tsp salt. Mix thoroughly.
Marinate the pork belly with 2 tsp salt, 5 spice powder, and wine. Let it sit for at least an hour before wrapping.
Meanwhile, prepare the rest of the ingredients, each in separate bowls. Marinate the mushroom in soy sauce and sugar. Dice the dried shrimp if pieces are unequal sizes. Soak the mung beans for at least 30 min. Chop the chinese sausage into 12 pieces. Cut up the egg yolk, if desired.
When you're ready to wrap, prepare the bamboo leaves by boiling them in water until softened and flexible. Have you string or twine ready for use.
Start with one leaf and create a cone, held in one hand. Do this by folding the length in half and then fold a corner over itself to seal one edge. You now essentially have 2 edges locked (crease on bottom and the fold). The fold should be held directly in your palm.
Begin filling the leaf, first with the rice and then the other ingredients, as desired. Leave a bit of room to add more rice to somewhat cover the ingredients.
Taking the second leaf, wrap it around the base of the first and make a fold on the other free edge closest to you. The folds should be facing each other. You should now essentially have 3 sealed edges.
Continue holding the bottom of the joong. You can switch off hands to get a better grasp. Gently tap the joong on the table to settle the filling. Top off with more rice without spilling over.
Grab all the leaves at the top with your free hand and fold them down neatly, perpendicular to the other edges. This should create a long tetrahedral (4 sided volume). You may need to tuck in and fold some edges in before folding all the leaves down together to create a neater look. You should be able to hold the whole joong in one hand.
Using your other hand, wrap the string around the joong a few times (use the hand holding joong to also hold down the string in the beginning). It should crisscross itself a couple times too, but most importantly, make sure the string holds down the folds and the tips of the leaves. Tie a secure knot. Congrats on making your first joong!
Repeat for 11 more joong. When you're almost done, start boiling a large pot of water. Place all the joong in the pot (add more water if necessary to keep from drying out). It's okay if the joong aren't fully submerged in water. Steaming works similar in the pot. Simmer for about 3 hours.
Drain, unwrap, and enjoy! Feel free to add a little bit of soy sauce or sugar (this is common!)
Notes
You can mix and match the ingredients to your liking. The ones marked optional are ones that aren't traditional or ones that I personally don't use as much
If you don't have 5 spice powder, you can substitute for an equal mixture of cinnamon, ground ginger, and cloves. Traditionally, 5 spice powder consists of star anise, fennel seeds, peppercorns, cloves, cinnamon.
You can sub shaoxing wine with another similar white wine or mirin
See the blog for pictures of wrapping the joong
Give yourself about 4 hours to start preparing before you want to eat it (and a few more hours ahead for soaking rice)
To re-use the bamboo leaves and string, soak them in water and scrape off all the food. Gently wash off the grease. Reboil the leaves to sterilize again, then air dry.