First, grind the pork loin using a food grinder. Run it through the food grinder twice for the smoothest texture. Add the ground pork loin to a bowl.
Add ½ tsp of garlic powder, ¼ tsp of white pepper, 2 ½ tsp of granulated sugar, 1 tbsp of corn starch, 2 tbsp of fish sauce, ¼ tsp of salt, 1 tsp of baking powder, and ¼ cup of ice water to the bowl. Mix until well combined.
Add the ground pork mixture to a Ziploc bag and freeze for 1 ½ hours. Flatten the ground pork so it's as thin as possible. This will help the pork reach the correct temperature faster. Save the Ziploc bag for later.
Empty the ground pork into the bowl of a stand mixer. Whip on speed 4 for 5 minutes. Increase the speed to 6 and whip for another 5 minutes. Transfer the ground pork back into the Ziploc bag and freeze for 40 minutes. Make sure to flatten the pork mixture.
After 40 minutes, empty the ground pork into the the stand mixer bowl, and whip on speed 6 for another 10 minutes.
Now you're ready to form your pork roll. Empty the pork onto some plastic wrap. Use the plastic wrap to help you form your pork roll. The pork roll should be in the shape of a cylinder with a 3 inch diameter and ~7 inches long.
Grease 1 banana leaf with oil and place it on top of the second banana leaf. Unwrap the pork roll and place it in the center of the banana leaves. Roll your pork roll tightly in the banana leaves and close the ends.
Finally, roll your pork roll in aluminum foil. This will help keep your cha lua tight and prevent moisture from getting in. Tie the pork roll tightly with cooking twine.
Prep your steamer by bringing water to a simmer and adding your steamer insert. Once the water is simmering, add in your pork roll and let it steam for 32 minutes.
Remove and let it cool down for at least an hour before serving.