Prepare the fish. Wash the fish and remove the scales. Fillet carefully, remove the bones and skin, then place the fish meat in a bowl.

Steam the fish. Chop the fish meat into very small pieces and steam for about 10 minutes, or until fully cooked and opaque. Let it cool.

Mash the fish. Mash the cooled fish with a spoon until fine and paste-like.

Make the mixture. In a large bowl, combine the steamed fish, grated carrots, spring onions, chopped onion, and garlic. Season with salt and black pepper.

Add the white sugar, cornstarch, all-purpose flour, and water. Mix thoroughly until a thick, pasty mixture forms.

Add the baking powder and mix well until evenly incorporated.

Shape the fishballs. Heat enough cooking oil in a deep pan over low to medium heat. Using two spoons, scoop portions of the mixture and shape them into small balls.

Carefully drop the fishballs into the hot oil, leaving enough space between them to prevent sticking.

Fry until golden brown and cooked through, turning gently as needed for even browning.

Remove the cooked fishballs using a slotted spoon and place them in a strainer or on paper towels to drain excess oil.

In a saucepan, combine the water, brown sugar, soy sauce, cassava flour or cornstarch, chopped onion, garlic, optional chili, and salt.

Stir thoroughly while the ingredients are still cold to dissolve the starch and prevent lumps.

Place the saucepan over medium heat and bring the mixture to a boil, stirring continuously.

Cook for 5–7 minutes, or until the sauce thickens.

Taste and adjust the sweetness, saltiness, or spiciness according to your preference.

Serve the hot fishballs with the freshly prepared fishball sauce.