Stir Fry Technique: Ten Steps to Better Wok Cookery
Regarding tapioca starch and arrowroot: yes, they can be used instead of cornstarch in all of my recipes. They perform the exact same function, however, in my experience, they are stronger binders, so you use -less- of them both in marinades and as thickeners. I would use about half as much of either of them as I would use cornstarch. Therefore, if you substitute either of them in one of my recipes, use half the amount directed for cornstarch.
Now, as to the first part of the question, I realized that though I have repeated the method that I use to stir fry umpteen-eleven times with each recipe I post, nowhere have I ever really truly explained it all, beginning to end. So that, when someone looks at my directions to "toss meat with soy sauce, wine and cornstarch, then allow to marinate for at least twenty minutes," they may follow those instructions, but they may never really know what function the cornstarch fulfills in the recipe. Extrapolating from the cornstarch mystery, I realized that there are likely oddities to my method that also may stump other readers, so I might as well slow down and record exactly what I am doing and why so that everyone is on the same page with me when they go to recreate my recipes.
So, from beginning to end, here is my explanation of my method of stir frying, which tends to differ in a few respects from the instructions one is apt to get in the average Chinese cookbook.
Step one: Cut your ingredients into equivalent-sized and shaped pieces.
This rule is quite effectively stated in all good Chinese cookbooks. In order for the food to cook evenly, quickly and aesthetically, the pieces must all be as close in shape and size as possible. If you examine photographs of my completed stir-fried dishes, you will note that most ingredients have been cut into similar shapes and sizes, as much as is possible given that vegetables and meats do not come in neat geometric shapes. I won't go into long explanations on how to manage the art of cutting for Chinese stir fry; that is an entire series of posts in and themselves, but I do want to emphasize the importance of cutting into shapes that will cook quickly.
Back when Morganna made her umami chicken stir fry, she cut the chicken into very large cubes, which is inefficient when it comes to stir frying. In order to get them to cook evenly without drying out, we ended up searing the outside of the chicken in the typical stir-fry method, then adding liquid and allowing the chicken to simmer, or braise quickly to finish cooking the interior. This noticably affected the taste of the final dish: the sauce was bland, as it had been watered down by the use of more wine and broth than is usual. When I pointed out that if she had cut her chicken into smaller, thinner bits, the extra liquid would never have been added, Morganna's eyes lit up with understanding as to why I tend to cut my meats into very thin slices or shreds. (Every step of a stir-fry is affected by every other step. In order to adjust for large chunks of meat, the sauce making is adapted, and can suffer.)
Step two: Marinate your meat or tofu in a mixture that includes cornstarch.
This step is the one that tripped Persimmon up. She understood the thickening property of cornstarch, and knew that somehow this action was in play when it came to using it in the marinade (especially since very few of my recipes have cornstarch added in a later step), but she could not fathom why it was used with the meat before it was cooked.
The main reason I add cornstarch to the marinade is because it holds the liquid of the marinade onto the meat: it makes it clingy. If you marinate meat with cornstarch in addition to the liquids, when you go to cook the meat, you will note that there is very little liquid left in the bowl after the meat is put into the wok. That is because most of it is clinging to the surface of the meat.
What happens to the liquid and cornstarch that sticks to the surface of the meat is one of the great secrets to building deep flavor in a very quickly cooked dish like a stir-fry. Much of it browns when it comes into contact with the wok, and helps brown the surface of the meat, thus adding to the flavor profile of the dish. And, through various other processes that I will outline in later steps, it helps thicken the sauce as it is formed through the cooking of the stir-fry. (I do not typically add a pre-mixture of sauce ingredients near the end of the stir-frying process. Generally, I add liquid ingredients during the course of the stir fry and allow them to thicken by the process of reduction or evaporation during the natural cooking process. This leads to a dish that has less sauce, but the sauce that there is clings tightly to the food, leading to a more beautiful appearance and is more highly and intensely flavored than a sauce that is simply poured in and allowed to thicken at the end of cooking.)
Step Three: Have all ingredients ready and lined up beside the wok, before you heat the wok.
I won't belabor this point;it is pretty straightforward. Stir frying goes quickly, so have everything cut, measured and put into prep bowls near your wok so you don't end up running around like a chicken with its head cut off while the food in your wok burns.
Step Four: Heat your wok until it begins to smoke, then add the oil and heat it until it nearly smokes.
This is only if you have a cast iron or carbon steel wok. If you have a nonstick wok, do not do this or you will ruin your wok. Only heat non-stick surfaces with oil or liquid in them. Assuming you have the cast iron or carbon steel wok, what you want to do is put it on your burner and get it as hot as you can. For most American stoves, flat bottomed woks work wonders, coming perfectly into contact with the heat source. Allow it to heat until the wok "exhales." This is when the scent of the hot, seasoned wok is released by the metal of the wok; it is the scent known in Cantonese as "wok hay." Until I knew the Cantonese term, I called it, inelegantly, "Wok smell." Now I call it "the breath of the wok." As soon as you can smell the wok hay, and see the pale ribbons of smoke rising from the hot metal, pour in your oil, and wait for it to heat up until it is nearly smoking. It will shimmer with convection currents when it is ready and the wok hay will intensify.
Step Five: Add your aromatic ingredients, in the order specified in the recipe and cook for a minute or two until they are fragrant and cooked to the point specified in the recipe.
This, again, is fairly self-explanatory. Aromatic ingredients include onions, garlic, ginger, shallots, scallions, chiles, chile flakes, spices (whole or ground) and ingredients such as dried shrimp or fermented black beans. The purpose of adding these intensely flavored and scented ingredients first is so that their essence can fully permeate the cooking oil and add their strong flavors to the food as it is cooked. This is the first step in the flavor-building process that continues throughout the cooking of an excellent stir-fried dish.
Step Six: Add the meat, settle it into a single layer in the bottom of the wok and leave it there for about a minute or so to begin to brown deeply on the surface touching the wok.
This step is essential to the home cook being able to recreate the special flavor of a wok hay-filled dish that is cooked in a restaurant. Home stoves do not put out the huge amounts of heat that Chinese restaurant stoves do. The heat of a wok stove and the use of large amounts of oil are most of what contributes to the special, undefinable flavor and fragrance of Chinese restaurant food that most people long to recreate. It is the flavor of the well-seasoned, very hot wok that you are smelling and tasting. You can come very close to recreating this at home, even if you do not have a stove with as many BTU's as mine. I discovered this technique by accident; I was once stir frying a dish, and the phone rang. As I was expecting a call, I answered it, but did not move the wok off the stove. I had a regular flat-topped electric stove, and had just put the meat in. I thus, left it to cook unsupervised. When I realized what I had done, I caught the wok in the nick of time and started stirring the meat madly; it had only browned on one side. When Zak and I ate, the dish was superb and tasted like it came from a restaurant. Years later, when Grace Young's book, The Breath of a Wok came out, she described the exact same technique as one she learned from her parents, both excellent Cantonese home cooks, and I realized I waonto something. When I later met Grace and shared notes with her, she agreed that no other Chinese cookbook author had ever instructed thier readers to cook in this way, which leads to people creating stir fries that do not taste right.
This is the most important step. Put the meat into the wok, slide it into a single layer on the bottom of the wok, and leave it alone. Do not stir it. Do not touch it. Leave it alone for around 45 seconds to 1 1/2 minutes, until you smell the meat and cornstarch marinade begin to brown. At that time, stir fry as normal, until the meat is mostly done, it has cooked 2/3 of the way, 2/3 of the surface has changed color to the color of cooked meat. You will note at this time, some small amounts of the marinade have stuck to the wok and begun to brown. Do not worry; it is supposed to do that, and you will take care of that in the next step.
Step Seven: Add soy sauce, wine or some combination of the two to the wok and deglaze the cornstarch marinade, and toss the meat to season it.
This is where you begin building the flavor of the sauce and you deepen the color and flavor of the meat. Soy sauce added at this point, in a small amount, will color the meat and deglaze the browned bits in the wok, thus creating a bit of liquid that is enough to season the dish, but not enough to change the cooking method to steaming or braising. You can use soy sauce alone, wine alone, or a mixture of the two at this point. You can also add sugar at this point, if required to in the recipe, again, allowing the sauce time to build its flavor profile bit by bit.
Step Eight: Add vegetables, in the order of how long they will take to cook, and stir fry.
This step continues the cooking process of the meat, and allows the vegetables to cook as much as they need to. Use your judgement as to how long the vegetables will take to cook and add the ones that take longest (carrots, for instance, or the thicker stems of gai lan) first, and the ones that barely need to cook (water chestnuts or snow peas) at the last.
Step Nine: Add broth, any other sauce ingredients such as oyster sauce, hoisin or vinegar, stir fry until sauce thickens and clings to the pieces of food in the wok.
This is where you finalize the flavor of the sauce and mix the ingredients thoroughly together. The amount of broth, if you use it, depends upon what you are cooking. If you are cooking gai lan leaves and want them to wilt, you use a bit more broth than usual, and allow the steam of it boiling away as it reduces to cook the leaves, making them wilt to a velvety texture. If you are not cooking anything leafy, then you use less broth, if you use any at all. At this point, after this step, you can remove the wok from the heat.
Step Ten: Add garnishes, and any last minute flavoring items like spices or sesame oil, put into a warmed serving plate and serve.
This is the final step where the last bits of flavor and color are added to give extra mouth and eye appeal to the dish. After this, all that is left is to wash the wok.
There it is: Barbara's Way of the Wok in Ten Mostly Easy Steps. I hope that it might have answered a few questions people might have had regarding my recipes, and I hope it might make the entire process a bit clearer in the future when you approach the art of stir-frying. It isn't all you need to know about stir frying by a long shot, but it is a good start. I came across most of this on my own, through trial and error, but a lot of it I learned in dribs and drabs from various, mostly out of print cookbooks. The sort of stir fry you will make out of using this method is one that has a sauce that is highly flavored from multiple reductions and a single deglazing. The sauce will not be plentiful, but will instead glaze the food ingredients and cling tightly to them, but the intense flavor more than makes up for a lack of sauce. This is the way a lot of Chinese homestyle cooking is done, with very little, but very flavorful sauces.