In a pan, mix onion, 1 thumb of sliced ginger, and goby, and season with salt, ground black pepper, green chili, 1 thumb of sliced ginger, and vinegar.
Cover the pan and cook for 10 minutes. After 10 minutes, pour the coconut milk into the pan.
Frequently stir the coconut milk until boil, then cover the pan and cook for 10 minutes over low heat.