Cut the bitter melon in half, and scrape out the seeds and the bitter white pith with a spoon.

Slice thinly, about 2 mm thick. Blanch in boiling water.

Squeeze out all the moisture from the blanched and drained bitter melon slices.

Combine the sugar, soy sauce, and vinegar in a pan and bring to a boil. Add the bitter melon and simmer over medium heat.

Simmer until there's no moisture left in the pan. Add the bonito flakes and sesame seeds at the end, and it's done.