Steam or boil the sausages for 10 minutes. Cool slightly, then dice and set aside.
Heat a large frying pan with 1 tablespoon oil over high heat. Stir-fry the garlic and ginger until aromatic, 2-3 minutes. Add the sausage and broccoli until soft, about 3-4 minutes. Add sugar and stir well.
Add enough hot water to cover 1/3 of the ingredients. Cover the pan with a lid and simmer for 2 minutes. Season with fish sauce to taste. Serve.