In a mixing bowl, whisk together soy sauce, oyster sauce, grated ginger, minced garlic, and sesame oil. Toss the beef strips into this marinade and let them soak for about 10-15 minutes.

Heat 1 tablespoon of vegetable oil in a skillet over medium heat. Add the sliced onions and sauté until soft and caramelized, seasoning lightly with salt and pepper. Once they’re perfectly golden, set them aside.

In the same pan, crank up the heat to high and add 2 tablespoons of vegetable oil. Toss in the marinated beef strips, sizzling away for about 2-3 minutes until they’re browned and crispy.

In a small bowl, combine the remaining soy sauce, oyster sauce, hoisin sauce, rice vinegar, and cornstarch. Pour this mix over your beef, letting it simmer until the sauce thickens and clings beautifully.

Stir in the sautéed onions, ensuring everything is well-coated and mixed. Serve while it’s hot, and watch it disappear over a bed of steamed rice or noodles.