First, let's prepare the ingredients. Detach the firm stalk from the cabbage leaves. Cut the leaves into bite-size pieces. This cabbage is known as spring cabbage, which has moist and tender leaves, and a loose head compared to the ones harvested in winter.
As for the stalk, thinly slice it using diagonal cuts.
Remove the seeds and stem ends from the red and green bell peppers. Japanese bell peppers are also known as Piman, and they have a relatively thinner skin/rind and a long oval shape. Cut the peppers into long bite-size pieces.
Trim the stem end of the shiitake mushroom, and detach the stem. Shiitake shrinks when cooked so cut the cap into relatively thick slices.
Thinly slice the stem so that it can also be used in the dish.
As for the white part of the long green onion, slice it into 5 mm (0.2") slices diagonally.
Let's make the sauce. In a bowl, combine the sweet bean sauce, sugar, sake, soy sauce, grated garlic, and potato starch. The sweet bean sauce is an essential Chinese condiment also known as tian mian jiang. Stir to combine thoroughly.
Now, let's make the twice-cooked pork. Line up the pork belly slices on a tray, and dust with potato starch. Coating the pork with potato starch will help keep the meat from becoming tough and also absorb more seasoning. Flip the pork slices over, and dust the other side as well.
Add vegetable oil to a pan and turn on the burner. Swirl the pan to coat it with the oil. Arrange the pork belly slices in the pan.
Cook the surface and flip them over.
When both sides are lightly browned, turn off the burner and place the pork onto a tray.
Clean the bottom of the pan with a paper towel. Add slightly over a half tablespoon of vegetable oil. Add the chopped ginger root, doubanjiang, chili bean paste, chopped douchi also known as fermented black beans. Turn on the burner and stir-fry on low heat.
Douchi is a Chinese condiment, in which salted black beans are fermented and semi-dried. It will add a more authentic taste, but you can also make delicious twice-cooked pork without using it.
When the aroma grows stronger, add the long green onion, bell peppers, and shiitake mushroom.
Turn the heat to medium and stir-fry the vegetables.
When the bell pepper begins to soften, add the spring cabbage leaves. Continue to stir-fry.
When the cabbage is coated with oil evenly, pour over the sake or water to help cook the vegetables. The hot steam circulates around the pile of the vegetables, cooking them quickly.
Occasionally turn the ingredients over from the bottom.
When all the vegetables soften, add the cooked pork slices, and turn off the burner. Thoroughly stir the combined seasoning from the bottom, and pour in the sauce.
Turn on the burner again, and quickly coat the vegetables with the sauce evenly on medium heat. Turning off the burner when adding the seasoning will give you extra time and help you to thicken the sauce evenly.
When the sauce is thoroughly thickened, drizzle on the sesame oil and distribute.
Place the twice-cooked pork onto a plate.
In authentic Sichuan-style twice cooked pork, pork belly block is simmered and cut into relatively thick slices before returned to the wok but you can also use easily available pork belly slices for yakiniku.
The moisture in the vegetables will be extracted while cooking, but giving it a thick consistency will help coat the ingredients with the sauce evenly.