Mix the fish sauce, water, chile garlic sauce, the lime juice, and sugar together in a small pan and bring to a boil.
Fill a large heavy saute pan with 1-inch of oil and heat for 5 minutes until hot, but not smoking.
Make 2 diagonal cuts on each side of the fish for ease of cooking. Salt, pepper, and flour both sides of the fish. Fish should be dry, as to not splatter oil when frying. Lower fish into oil, the oil should bubble vigorously. Cook 4 minutes on each side until golden brown. Check cuts on fish for doneness.
When fish is almost cooked, heat up sauce and stir in cornstarch mixture while sauce is boiling. Sauce should be slightly thick, but not lumpy. Remove fish from oil and slightly dry with paper towels. Add scallions to the sauce and pour over fish to cover. Serve with steamed rice.
This recipe was provided by a chef, restaurant or culinary professional. It has not been tested for home use.