Make the sauce: In a wide, heavy bottomed pot, heat the olive oil over medium-high heat. Place the sliced onion into the pot and saute for 4 minutes.  Lower the heat to medium-low, cover and allow to soften for 15 minutes. Stir the onions every 5 minutes or so. Pour the crushed tomatoes, ¾ cup water, tomato paste, 1 teaspoon salt, ½ teaspoon white pepper, the cane sugar and bay leaves into the pot and stir. Reduce the heat to low and simmer for 30 minutes, adding up to 1 cup of water to achieve the desired consistency. 

Prepare the fish balls: In a food processor pulse the fish, chopped onion, eggs, cilantro, 1 tablespoon salt, 1 teaspoon white pepper, nutmeg, mace and sunflower oil. With oiled hands, form 24-26 balls, about 60 grams each. Place them onto a parchment-lined baking sheet.

In a medium sized pot, bring water to a boil with 1 teaspoon of salt and a spoonful of sauce. Carefully place the fish balls into the water and cook for 5-7 minutes. This allows the balls to firm up before going into the sauce. Do this in batches. 

Place the fish balls into the sauce and simmer, covered for 10-15 minutes until they are cooked through.