Qing zheng yu (清蒸鱼, literally clear-steamed fish) is the benchmark of Cantonese cooking — a whole fish steamed with minimal seasoning so that the quality and freshness of the fish is the entire point. The technique is deceptively simple: steam a fresh fish above boiling water for precisely the right amount of time (over-steamed fish is dry and fibrous; under-steamed fish is not safe to eat), dress with soy sauce and fresh ginger and scallion julienne, then pour sizzling hot oil over the surface to bloom the aromatics. The success or failure of the dish is almost entirely determined by the quality of the fish and the precision of the cooking time.
The fish: Whole, fresh. In Cantonese tradition, a live fish is ideal — the clear eyes, bright red gills, and firm flesh of a just-killed fish are visual indicators of quality. Sea bass (lu yu), grouper (shi ban yu, 石斑鱼), and pomfret (chang yu, 鲳鱼) are classic choices. Preparation: Score the fish on both sides (2-3 diagonal cuts to the bone) to promote even cooking. Rub the interior and scoring with a small amount of light soy and Shaoxing wine. Place 2-3 scallion stalks and 3-4 ginger slices inside the cavity and under the fish (elevating the fish above the plate slightly promotes even steam circulation). The timing: This is the critical variable. For a 600g whole sea bass: 8-10 minutes in a steamer over rapidly boiling water. The fish is done when the flesh at the thickest point flakes easily when tested with a chopstick. Any longer and the flesh becomes dry and separates from the bone. The finish: Scatter julienned ginger and scallion generously over the surface of the cooked fish. Pour 2-3 tbsp of soy sauce over. Heat 3-4 tbsp of neutral oil in a wok until just smoking. Pour the hot oil in a thin stream over the fish — it sizzles against the soy sauce and aromatics, releasing the final bloom of fragrance.
Oversteaming: 2 minutes over the ideal cooking time produces a dry, tough fish. The most critical timing error in Chinese cooking. Insufficient steamer heat: The steam must be at full force when the fish enters — a partially heated steamer extends the cooking time unevenly.
Fuchsia Dunlop, Land of Fish and Rice (2016); Eileen Yin-Fei Lo, Mastering the Art of Chinese Cooking (2009)