Wash fish and dry thoroughly. Heat oil on high setting and briefly fry fillets on both sides until golden. Drain on paper towels. Pour off all but 2 teaspoons of oil. Fry garlic until light brown. Add soy sauce, sugar, fish sauce and tamarind liquid. Cook for 1 minute. Carefully return fish to this sauce. Sprinkle with ginger and green onions and cook for 2 minutes. Spoon sauce over fish. Serve sprinkled with the onion flakes.