Seriously Asian: The Passing Through Technique
Principles of Stir-Fry, Part Two
In Chinese households, home cooks stir-fry dishes but they bear little resemblance to restaurant counterparts. For the native Chinese eater, going to a Chinese restaurant is the equivalent of say, an American family of European lineage going out for French cuisine. There are similarities--the pâtés and terrines may evoke the meatloaves cooked at home--but the differences seem far greater.
Restaurant fare appears more complicated and quite often, tastes more sophisticated than a home-cooked meal. Eating at a Chinese restaurant, you wonder if home cooks are unable, or simply unwilling, to replicate the dishes of professionals.
What accounts for this discrepancy? And can these differences be bridged? For better or worse, Chinese restaurants deep fry almost everything at some point. They commonly apply the "passing through" technique, or guo you, in which foods are briefly par-fried prior to more cooking. "Passing though" is a preliminary stage in the process but undeniably affects the end result.
By passing items through a shallow pool of hot oil, the flavors can be sealed in--their shapes preserved and solidified--while the textures remain tender. "Passing through" is, essentially, a shallower and gentler form of deep-frying, so home cooks can easily apply the technique.
To start, food is passed through the pool of hot oil, then removed from the wok. Almost all of the oil is poured away and what's left is used to finish the stir-frying process. In the last moments, the passed-though items are stir-fried with the rest of the ingredients in the wok. While deep-frying with many quarts of oil isn't ideal for all home cooks, "passing through" requires only about two cups of oil. As a result, the bottom of the wok fills with one to two inches of oil, which only needs to be heated at 300 to 325°F. At this milder temperature, the oil is hot enough to cook the food but not hot enough to brown it, which would happen in a true application of deep-frying.
Restaurants use the "passing through" method for many reasons, yet the technique is even more important for the home cook. Lacking the incredible heat of a restaurant stove or the powerful vents that siphon grease from the kitchen, home cooks must stir-fry on a smaller scale. By passing items through hot oil for a short amount of time, the benefits of intense heat can be gained without access to professional equipment.
In passing through, the items almost always marinate in cornstarch and egg, both of which helps form a thin, protective film. When adding the items to the wok, do so carefully, making sure you don't splash the hot oil. Do this in rapid succession so the pieces don't clump together. Since the temperature will drop when the items enter the oil, you may need to increase the heat to counter the drop. Passing through should take no longer than a minute, as the items should be removed just when they have firmed up.
As with most cooking techniques, the ingredients are not as important as mastering the method itself. You can use an array of proteins--chicken, beef, pork, shrimp, and fish--as well as seasonal vegetables I took advantage of the zucchini and squash in season, pairing the mellow vegetables with a mellow fish.
Basa, a subtle and unassuming fish, tastes much better after the passing through method. The fillet's texture remains firm yet tender, and won't flake apart during a subsequent stir-frying. Other firm-fleshed white fish, such as sea bass or grouper, are options.
In restaurants, the dishes have a rounded-out, meaty taste from all the lard and good stock used. Recently, Chinese mothers have begun shying away from lard. Pork fat, though more fragrant (xiang) than vegetable oil, is used sparingly if at all given the spread of fat-phobia. To give your dishes a meatier depth, replace some of the oil with lard when you are stir-frying in the latter stages.
Seriously Asian: The Passing Through Technique
About This Recipe
- 2 cups oil for passing through
- 10 ounces firm-fleshed white fish fillets, such as basa
- For the marinade:
- 1 teaspoon Shaoxing rice wine or sake
- 2 teaspoons cornstarch
- 1 egg white
- 1/2 teaspoon salt
- a pinch of ground white pepper
- For stir-frying:
- 2 tablespoons of lard
- 1 medium-sized zucchini and 1 yellow squash, or 2 of either
- 1 green onion, sliced into thin slivers
- 1/4 cup fish or chicken stock
- 1 teaspoon salt, or to taste
- For the slurry:
- 2 teaspoons starch
- 2 teaspoons cold water
To prepare the fish: Cut each fillet of fish into 2-inch segments.
To marinate the fish: Beat the egg white until it is frothy, and combine with the alcohol, cornstarch, salt, and pepper in a medium-sized bowl. Add the fish and mix gently so that each piece is coated in the marinade. Let stand for 15 to 30 minutes.
In the meantime, wash the zucchini and squash. On a bias, cut the vegetables into half-moon slices so that each piece tapers off on one side. Set aside.
Pour out all but 1 tablespoon of the oil in the wok, and add 2 tablespoons of lard. Add the green onion and stir-fry for about 10 seconds, until the oil is fragrant. Add the pieces of zucchini and squash, and rapidly stir-fry for a few minutes - just until the vegetables are cooked through, but still very crisp. Salt to taste, about 1 teaspoon.
To make the slurry: In a small bowl, dissolve the cornstarch into the water. Have the bowl on hand. You may need to briefly re-mix the slurry right before you use it.
Return the pieces of fish back to the wok and pour in all of the fish stock. Simmer over low heat for about 10 seconds; then add the cornstarch slurry and mix gently, taking care not to break up the fish. Let simmer gently for about 30 to 60 seconds, until the vegetables and fish are evenly coated with the stock, which should have thickened with the cornstarch addition. Serve immediately.