Set a large, heavy skillet over medium-high heat and sprinkle the sugar over the bottom.
Cook until it starts to melt and caramelize, and stir to help it along. (Don’t worry if it clumps—it will remelt.)
Add the pork and stir to coat. Continue to cook for 5-10 minutes, until the meat is opaque and starting to caramelize.
Stir in the fish sauce, garlic, sesame oil, ginger, chili flakes and a big pinch of salt.
Cook, stirring often, for 10-15 more minutes, or until the pork is deep golden and cooked through.
Stir in the green onions (reserve some to sprinkle overtop, if you like) and serve with steamed rice.