How to Make Restaurant Style Stir Fry
My family owned Chinese restaurants and I watched the chefs cook for years and experimented at home to get that "restaurant style" taste.
One thing the cookbooks don't tell you is that restaurants DEEP FRY their meats and vegetables in A LOT of oil in the bottom of the wok first, meat in one batch, vegetables in another. Then they scoop out the meat and veggies to strain on a strainer they keep on top of the big container of oil that they re-use for this purpose.
Next the cook makes a sauce in the wok, whatever soy sauce-based brown sauce they use, then add Sa Cha or black bean sauce or whatever flavor they're making. For white sauce they just start with stock and add garlic and seasonings. They let the sauce heat to boil, then they dump the meat and veggie in the sauce, flip a few times to incorporate, and that's it. Some dishes have more sauce, and they thicken with a cornstarch slurry at this stage. But if you have the right amount of sauce thickening isn't even necessary - just the right amount sticks to the oil on the meats and veggies.
Frying the meat and veggies first like this gives them a crispy texture that you can't get from "stir frying" with 2 tablespoons of oil. Home stir fry techniques always end up with a lot of moisture from the meats and veggies in the pan, and the food is more boiled/steamed.
Anyway, I've been able to come close to restaurant style stir fry by frying the meat and veggies in about an inch of oil that I keep in a small sauce pan, then using a wide strainer to scoop them out to drain on a paper towel lined bowl while I make the sauce. Keep the oil, because it actually picks up the flavor of the foods you fry in it, and adds to your dish. Just keep adding fresh oil as needed and straining it through paper towels or a coffee filter once in a while.
As for the sauce, that's easy, and don't be afraid to experiment. I usually just make it on the fly in the pan (I use a chef's pan or sauce pan, but a flat bottom wok is fine too). Try some of these combinations:
1. Low sodium soy sauce, rice wine vinegar, cooking wine, Mirin (or sugar) for a brown sauce that's like the one restaurants use on green bean dishes. Add red pepper flakes if you like spicy. Great with Japanese eggplants too.
2. Low sodium soy sauce, wine, oyster sauce. Like restaurant beef and broccoli.
3. Chicken stock or water, chopped garlic and/or ginger and/or scallions, thickened with cornstarch slurry for white sauce. For white sauce chicken or seafood dishes. Add a beaten egg right before removing from pan, let sit for a few seconds before stirring, and you have Lobster Sauce. (If you want to make old school traditional Lobster Sauce, you'll also need to add some ground pork when starting the sauce. I've used country sausage with ok results.)
4. Low sodium soy sauce, cooking wine, Sa Cha sauce or Black Bean sauce (you can buy prepared mixtures) for whatever spicy brown sauce you like from the restaurants.
But the key to all this is the deep frying. Try it with green beans and you can really tell the difference. They get that chewy caramelized taste and texture that I love but was never able to get with any other method.
Good luck.