Stir-fries are the ideal way to use up vegetables—or even parts of vegetables—that you'd otherwise not know what to do with. Take, for example, leek greens. Nearly every leek recipe out there uses the white parts only, advising you to save the greens for stock. But let's get real: there's only so much stock you can make.
Fortunately, leek greens (so long as they aren't coming from those super-sized fibrous leeks) are ideal for stir-frying. They're wonderfully aromatic, with a chive-like flavor. And though they're not as tender as the white parts of the leek and require a longer cooking time, the benefit is that they get more time to mingle with aromatics like garlic and chiles. In this recipe, I pair leek greens with onions and beef, stir-fried in a sauce flavored with fish sauce, soy sauce, sesame oil, dried chiles, and plenty of garlic.
There are a few keys to successful wok cooking, starting with cutting your meat and vegetables into bite-size pieces that will cook quickly and evenly. (Check out our Wok Skills 101: Stir-Frying Basics for more details.)
No one wants to follow a bite of tender sliced beef with a piece that's tough, chewy, and overcooked. Even slicing will help prevent that from happening. For this dish, I'm using my favorite stir-fry cut: flank steak. Flavorful and lean, it cooks quickly and is especially great at soaking up marinades.
Since flank steaks are best cooked to medium rare, there's no need to slice it paper thin for stir-fries (I like to cut it slightly thicker than 1/8 inch), but do remember to slice it against the grain for optimal tenderness. Once your beef is sliced, mix up your marinade, pour it on the beef, combine, and let it marinate in the fridge for at least 30 minutes or overnight.
The marinade not only seasons the meat, but also tenderizes it with the help of soy sauce, which contains enzymes that break down proteins.
Because they can be gritty and sometimes even muddy, I like to slice leeks at the very end, when I know I won't need to use the cutting board immediately afterward. Some folks like to split the leeks in half and wash them before slicing them, but I find it easier to remove all the dirt if I save the washing until after they're cut. I slice my leeks in half lengthwise, then into 1/2-inch pieces crosswise. I wash those pieces in a big bowl of water two times before I drain and spin-dry them in a salad spinner.
This drying step is crucial: wet leeks will cool down your wok, robbing you of that good smoky stir-fry flavor.
You can get small, hot dried red chiles at most Asian markets, or order them online. Either way, they should be dry but still pliable for the best flavor.
The easiest way to cut them is with a pair of kitchen scissors. Depending on the brand of dried chiles, the heat intensity varies, so taste a little before you commit. Discarding the seeds will also cut back on heat. For me, 12 dried chiles is the perfect amount of heat. It's not mouth burningly spicy, but you can notice the kick. If you're adding over 15 chiles, cut the chiles in half rather than into four pieces—you don't want your dish to look like it's just a plate of stir-fried chiles (or maybe you do?).
The next key to great stir-fries? Be prepared. Have all of your ingredients prepped, placed into bowls, and within arm's reach of the stovetop, because once you start cooking, there's no break until you're ready to serve.
In restaurants, powerful burners let cooks stir-fry everything in the same pan. At home, it's best to cook in batches in order to conserve heat. I start by heating oil (make sure your wok is smoking hot, and don't forget to crank up the exhaust fan!), and then add half of the chiles and some sliced garlic, allowing their flavor to infuse into the oil before using that oil to sear and color the marinated meat. The goal is medium-rare meat with a good seared crust, so it should only take a couple of moments.
Once the beef is cooked, I set it aside to make room for the vegetables.
In goes more oil, garlic, and chiles. Once the aromatics are fragrant, I add the leeks and onions. I cut my onions into a dice, rather than slices, so that they're roughly the same size and shape as the leeks. This helps them cook at the same rate, so you can throw them into the wok together.
Once the vegetables hit tender-crisp, I add the beef back to the wok and toss everything together before adding in my pre-mixed sauce ingredients.
This is a relatively dry stir-fry—the sauce should just barely coat the ingredients, seeping into cracks and giving the whole dish a nice clean flavor. Like I said, once you start stir-frying, you can't stop until the food is on the plate and ready to be eaten, so make sure your guests are ready, too!
Final key to a great stir-fry? Serve it HOT. This means using a heated plate, which you can warm up either in an oven or by running under hot water in the tap. This will help ensure that your beef and leeks are piping hot when they land on the table. All it needs is a side of white rice and dinner is served.