- Cut the fish into 2 inch by 3/4 inch (5cm by 2cm ) pieces. Mix the rice wine, 1/4 tsp. of the salt, the pepper, and the sesame oil and add to the fish. Let marinate.
- Dust the fish pieces with 4 tbsp cornflour. Dissolve the remaining 1 tbsp of the cornflour in 2 tsp. water. Set aside.
- Heat the oil in a wok over high heat to very hot, about 350oF(180oC). Add the fish piece by piece and deep-fry until brown. Remove, drain, and place in a dish. Pour all but 1 tbsp of the oil out of the wok. Add 4 tbsp water and bring to a boil over high heat. Add the milk and ketchup, and stir until the mixture boils again. Add the remaining 3/4 tsp. salt (or to taste), the cornstarch-water mixture. Cook, stirring, until thickened. Pour the sauce over the fish, sprinkle with ground sesame seed, and serve.