1lb (453 grams) beef flank steakthinly sliced against the grain (see notes within text)
3tbspneutral oil (I use avocado or grapeseed)
½onion (100 grams)finely chopped
4green onions or scallionscut diagonally into 2-inch strips
sesame seedsoptional, for garnish
white ricecooked (for serving)
In a medium bowl, marinate the sliced beef with the ingredients listed under marinade. Cover and set aside. You can also refrigerate this for a longer marination until ready to use.
Meanwhile, combine the ingredients for the sauce. Keep the rest of the ingredients for stir-frying near the stovetop. This is also a good time to prepare the rice if you haven't already.
Heat a wok or skillet over high heat and add the oil. Once hot, use tongs to lift the meat pieces and brown them over high heat for about 1-2 minutes on each side. Do this in batches to prevent overcrowding the pan. Be careful as there will be some splattering of the oil. Also be sure not to overcook the meat, as you want it to remain as tender as possible. Remove and set aside on a plate.
In the same pan, add the onions and sauté until they are slightly brown, about 2-3 minutes. Add the garlic and ginger and continue to sauté for a minute.
Pour in the sauce and mix well. Let this simmer for about 10-15 seconds, stirring constantly, and add the beef. Stir-fry for a couple of minutes until the beef is cooked through and the sauce has reduced down to the desired consistency. Taste and adjust salt and spices.
Mix in the green onions. Sprinkle with sesame seeds, if using. Serve immediately with white rice.