Make the sauce first. In a wide pan, fry the garlic in oil till the aroma rises. Add the tomatoes, tomato paste, sugar, salt, and chili pepper or cayenne. Add about 2 cups (500 mL) of water and bring to the boil. If you leave the chili pepper in throughout the cooking, the sauce might end up too hot for you, so taste the sauce and remove the pepper when you feel the sauce is hot enough.
For the fish balls, mix all the ingredients together and work to a firm paste with your hands. (If you use the food processor to grind the fish, do so very briefly or it can turn into a creamy puree.)
Take lumps of paste the size of a small walnut and roll into little balls.
Drop them one by one into the sauce and simmer for 20-25 minutes turning them over once.