📖 Instructions

1. Get started by slicing the beef: Take your flank steak and slice it thinly against the grain. Aim for pieces about 1/4 inch thick. This ensures the beef will be tender and absorb the marinade well. Place the sliced beef in a mixing bowl.
2. Make the marinade: In a smaller bowl, whisk together the soy sauce (or coconut aminos for gluten-free), brown sugar, minced garlic, grated ginger, and a pinch of black pepper. Pour this mixture over the sliced beef, ensuring every piece is coated evenly. Let the beef marinate for at least 20 minutes. If you have more time, marinating it in the refrigerator for up to a couple of hours will deepen the flavor. The longer it marinates, the more tender and flavorful it will become. The aroma at this stage is simply mouthwatering!
3. Prep your veggies: While the beef marinates, prepare the rest of your ingredients. Slice the onion into thin wedges and set aside. Chop the green onions into 1-inch pieces, separating the white and green parts. Set the white parts aside to cook with the onions, and keep the green parts separate for garnishing at the end. Have all your veggies ready to go; this stir-fry cooks quickly!
4. Mix the sauce: In another small bowl, combine the hoisin sauce, soy sauce (or coconut aminos), water, cornstarch (or arrowroot powder), sesame oil, and red pepper flakes (if using). Whisk until smooth, making sure there are no lumps of cornstarch. This sauce is the heart of the dish, providing that rich, savory-sweet flavor.
5. Sear the beef: Heat a wok or large skillet over high heat. Once it's hot, add a tablespoon of oil. In batches, sear the marinated beef until browned on all sides, about 2-3 minutes per batch. Don’t overcrowd the pan; searing in batches ensures the beef gets a nice crust. Remove the beef from the wok and set aside.
6. Sauté aromatics and onions: Add another tablespoon of oil to the wok. Add the sliced onions and the white parts of the green onions. Stir-fry until the onions are softened and slightly caramelized, about 3-4 minutes. The scent of the onions caramelizing is just divine!
7. Combine and simmer: Return the seared beef to the wok. Pour the sauce over the beef and onions. Bring the mixture to a simmer, stirring constantly until the sauce thickens and coats the beef, about 1-2 minutes. Be careful not to overcook the beef at this stage; you want it to remain tender.
8. Garnish and serve: Remove the wok from the heat. Garnish with the green parts of the green onions and sesame seeds. Serve immediately over steamed rice or noodles. Enjoy this flavorful and comforting Mongolian-inspired beef stir-fry!