Cut bamboo shoots into bite-sized wedges along the fibers for the upper part. For the bottom to middle part, slice them into rectangular pieces against the direction of the fibers, each about ¼-inch (6mm) thick.
Heat sesame oil in a pan over medium heat. Once the pan is warm, add the sliced bamboo shoots and sauté them lightly until they are evenly coated with oil.
Add seasonings (chicken stock, sake, mirin, and soy sauce) to the pan and bring it to a boil. Once boiling, reduce the heat to medium-low and let it simmer, turning the bamboo shoots halfway through, until most of the liquid has evaporated.
Add la-yu to the pan and briefly stir-fry everything together.
Place the bamboo shoots in a container and wait for them to cool down. Then, let them chill in the refrigerator for at least 3 hours.