Pork Sous Vide
Warm up the soud vide water bath to 77°C. Puree all your marinade ingredients together at once in a food processor, soy sauce, mirin, sugar, fish sauce, spring onions, garlic and ginger. Place the whole pork belly with the marinade into a vacuum seal bag and seal it tightly.
Otto's tip: put the content of the vacuum bag over the edge of the counter when vacuuming, so that no liquid gets sucked up.
Put the bag in a pot of water at 77°C and leave it in for about 10 hours. After 10 hours, take the bag out of the water and quickly cool it down in a bowl of cool water. Then, dry the bag and put it in the fridge. The sous vide pork belly can be stored in the fridge for up to two weeks.
Pork Belly Marinade
When the fat has become solid, open the vacuum bag and take out the pork belly. Remove the solid fat pieces and pour the jellied substance into a small pot. Heat it up until the jelly melts completely and then strain it for any remaining fat pieces. Pour the strained liquid back into the pot and let it simmer for 10 - 15 minutes on medium heat until it reduces to 2-3tbsp. It is important to make sure that the liquid doesn't burn.
Take the pot with the reduced liquid off the stove and let it cool down slightly. Put the mayonnaise in a bowl and add the liquid to the mayonnaise little by little while stirring constantly.
Crisp up the Pork Belly
Preheat the Otto Grill to 800°C for 3 minutes. Cut the sous vide pork belly into 0.5 inch thick slices, cutting with the grain, so that they are just the right size to fit on the pork belly bun. Put these on the cooled grill grate and into the Otto Grill. Set the Meat-O-Meter to stage 2 and sear the pork belly for one minute on each side using the highest flame setting to ensure crispiness.
Pork Belly Bun
Steam the bao buns in a bamboo steamer or a pot with a steam function for 2-3 minutes. Cut the steamed bao buns into halves and spread the umami-mayonnaise sauce on both sides. Fill the steamed bao buns with lettuce, a slice of pork belly and a slice of pickle. Serve and enjoy right away. There you go: homemade pork belly bun!