After the caramelized sauce is reduced by half, carefully add blanched catfish in piece by piece. Bring the heat to medium high and continue cooking.
The sauce will form many bubbles on top of the catfish surface, this is totally normal. Just remember keep an eye on the pot. DO NOT go anywhere or multi task at this point.
Cook for approximately 10 minutes or until the sauce reduce almost by half again. You can check the consistency of the sauce by using the back of a spoon. Dip a spoon into the sauce, if it is coated with the sauce and there is no dripping down. The sauce is done.
Turn off the heat. Add ground black pepper and chopped green onion for garnish. Enjoy with a hot bowl of steamed rice.