I started making this beef stir fry when my kids were going through their "I only eat plain food" phase. Somehow, getting them involved in choosing colorful vegetables and watching everything sizzle in the wok made dinner exciting again. This recipe has become our go-to weeknight meal because it's fast, uses whatever vegetables are lurking in the crisper drawer, and tastes so much better than takeout. The key to great stir fry isn't fancy ingredients. It's about high heat and timing. I learned this from watching my neighbor, who grew up in a Chinese-Jewish household and could make magic happen with a simple wok. She taught me that you need to get your pan screaming hot before adding anything, and never crowd the ingredients. That's how you get those beautiful caramelized edges on the beef and crisp-tender vegetables. I use flanken or minute steak for this because they're already thin and cook quickly. The marinade is simple but important. Soy sauce, a touch of sugar, and cornstarch create that glossy coating you see in restaurant stir fries. The vegetables can be whatever you have on hand, but I always include bell peppers for sweetness and snap peas for crunch. This works perfectly over rice or noodles for a complete meal. Sometimes I'll serve it with some crispy roasted potatoes on the side for extra substance. The whole thing comes together in about 20 minutes, which makes it ideal for those nights when everyone's hungry and patience is running thin.