Liu (熘) — Slippery Fry: Velveting Plus Quick Sauce Coating
Liu (熘) is the Chinese technique of pre-cooking a velveted protein in oil or water, then returning it to the wok with a pre-thickened sauce that coats and clings. The result is called slippery (hua 滑) because the cornstarch coating gives the protein a smooth, yielding texture quite different from the rough char of bao. Liu is central to many Cantonese restaurant preparations — sweet and sour pork, lemon chicken, and silk-textured prawn dishes all use the liu principle.
The liu sequence: 1. Velvet the protein. 2. Pre-cook: oil blanch (guo you) at 120C for 30-60 seconds, or water blanch at 80C. 3. Drain. Protein is now 80% cooked. 4. Make sauce separately: aromatics, liquids, and a cornstarch slurry that thickens to coating consistency. 5. Return protein to wok. Toss 30 seconds — sauce coats every surface. Sauce consistency: a sauce that flows off a spoon in a thick continuous stream and leaves a coating visible for 10 seconds.
Over-thickened sauce: Too much cornstarch produces a gelatinous, gummy coating. Cold protein returned to wok: The protein must be warm when it re-enters the sauce.
Irene Kuo, The Key to Chinese Cooking (1977); Eileen Yin-Fei Lo, Mastering the Art of Chinese Cooking (2009)
Common Questions
What are common mistakes when making Liu (熘) — Slippery Fry: Velveting Plus Quick Sauce Coating?
Over-thickened sauce: Too much cornstarch produces a gelatinous, gummy coating. Cold protein returned to wok: The protein must be warm when it re-enters the sauce.