Velveting works in two moves, not one. First a marinade — cornstarch and egg white, or a baking soda rub — changes what the surface of the meat does under heat. Then a fast dip in hot water or oil, thirty seconds to a minute, sets that change before the meat gets anywhere near a screaming-hot wok.
Two different marinades doing two different jobs
Cornstarch and egg white build something physical: swollen starch granules and coagulated egg white form a thin film wrapped around each piece, a barrier that keeps high heat from hitting bare meat directly. Baking soda does something chemical instead. It raises the pH at the surface, and muscle proteins bind to each other a little less tightly in that environment, so they hold onto more of their own moisture. Nothing is sealing anything in from outside — the meat itself changes.
Most recipes pick one or the other. Combining them is possible but rarely necessary; the coating and the alkaline treatment are solving the same problem from opposite directions.
The starch marinade, by ratio
For thin-sliced chicken or beef, work with roughly one tablespoon of cornstarch and one egg white per pound of meat, plus a teaspoon of oil and a tablespoon of rice wine or soy sauce for seasoning. Toss until every piece is coated in something closer to a thin, translucent paste than a stiff batter — a marinade too thick to move freely around each slice will clump instead of coating evenly. Fifteen to twenty minutes at room temperature is enough; longer just waits in the fridge.
The baking soda marinade, by ratio
Dissolve about a half teaspoon of baking soda in a tablespoon of water per pound of meat, toss it through, and give it fifteen to twenty minutes. Any longer and the surface goes past tender into slack and mushy. Rinse it off thoroughly before it goes anywhere near the marinade or the pan — undissolved baking soda left on the surface tastes like exactly what it is once it hits heat, the same soapy, mineral note a heavy-handed soak leaves behind.
Blanching in water or oil
Water just below a simmer, around 200 to 210°F (93–99°C), or oil at 275 to 300°F (135–150°C), both do the same job: set the coating or firm the surface before the intense heat of the wok. Thirty seconds to a minute is usually enough for thin slices. Add the meat in a single layer, or spread the pieces apart with chopsticks or tongs the moment they go in — meat dropped in a clump cooks unevenly and the pieces fuse together.
Water is more forgiving if you don't have a thermometer, since it can't run away from you the way oil temperature can. Oil finishes slightly drier and is the version most restaurant kitchens use.
How to tell it's working without a thermometer
The color is the clearest signal. Raw, marinated meat looks pink or translucent going in; it should turn pale and matte within thirty to forty-five seconds. If it's still slick and glassy-looking a minute in, the water or oil wasn't hot enough.
Feel matters too. Pull a piece out and press it — it should give slightly and spring back, not feel mushy or slip under your finger. Pieces should separate cleanly from each other in the pan rather than sticking into a mass.
Smell tells you about the baking soda method specifically. Rinsed meat shouldn't carry any sharp, chemical edge. If it does, the rinse wasn't thorough enough.
Why the blanch isn't the whole cook
This is a food safety line, not a texture preference. A thirty-to-sixty-second dip doesn't reliably bring chicken or beef to a safe internal temperature, no matter how opaque the outside looks. The wok stage afterward — high heat, constant motion, a couple of minutes — is what actually finishes the meat. Velveted meat that's pulled from the blanch and served without that final stir-fry is undercooked meat with a good texture, not cooked meat.