There seems to be some magic involved in achieving brilliant green broccoli with firm yet tender florets and pieces of stalk that are tender, not fibrous. Stir-frying is one way to achieve this. But it matters how small the broccoli is cut, as well as how hot and how long it's cooked. While some dishes feature large broccoli florets with stalks intact, most Asian-inspired stir-fries feature vegetables that are cut to about the same small size. There's a good reason for this.
Preparing the Broccoli
As with all stir-fry recipes, the key is to prepare everything first. Cut up all the ingredients and have them ready to go in order of what cooks the slowest. If you're using fresh broccoli, cut the florets off of the stalks, and then further chop large florets so they are the size of the smaller florets. Peel the stalks and chop them into something like 1/4-inch pieces. The key is to keep the sizes uniform. The stalks will go into the wok or skillet before the florets, because they take longer to cook.
Cooking Hot and Fast
Traditional stir-fries are cooked in a wok with a small amount of oil over a large flame for two to three minutes. The advantages of using a wok are its large surface area and high sides which allow for quick stirring. The ingredients should be stirred constantly to ensure everything cooks evenly without burning or sticking. This is the main reason why cutting the broccoli -- and other vegetables -- into small or thin, uniform sizes, is important.
Broccoli is a nutrient-dense vegetable. When cooked properly, it retains high levels of vitamins A, C and K. The advantage of stir-fry cooking is the ability to maintain both flavor and nutritional value by cooking quickly. Limp, mushy broccoli has fewer of most of broccoli's healthy benefits.
Sometimes it makes sense to steam before stir-frying. One of these instances is when you're using frozen broccoli. Frozen broccoli takes much longer to cook and the extra water from the frozen outer layer will result in stewed or steamed food, instead of stir-fried. The other time to consider steaming first is if the recipe requires the use of large broccoli florets. In both cases, the broccoli florets should be spread out in the steaming basket to allow for even steaming and, once the water boils underneath, cook the broccoli for three to five minutes. It should still be firm and bright green when you toss it into the stir-fry to finish cooking.