Mix the corn flour, tapioca starch and salt in a bowl then dry rub the fish and marinade for 30 minutes.
When ready, heat the 1/2 cup of cooking oil on a high heat. When hot, fry the fish 2 minutes per side, with the skin side down first. Set aside and rest.
In the same wok, leave behind 3 Tbsp of cooking oil and fry the shallots, ginger and garlic until fragrant (10 seconds). Next add the cucumber and tomato and cook for a minute. Then add the sauce mixture, mix well and cover with a lid. Cook for a minute.
Add the starch solution and reduce the liquid until your desired consistency. Serve the fish on a serving plate and drizzle the sauce on the fish.
