Prepare the Marinade: In a mixing bowl, combine the sliced beef or pork with white sugar, dark soy sauce, and a pinch of white pepper.

Prepare the Sauce: In a small bowl, whisk together the oyster sauce, Golden Mountain sauce (or soy sauce), and water. Set aside.

Cook the Meat: Heat 2 tablespoons of oil in a large skillet or wok over medium-high heat. Add the marinated beef or pork and stir-fry for 2–3 minutes until browned and nearly cooked through.

Sauté Aromatics and Vegetables: Add the remaining 1 tablespoon of oil to the skillet. Add the chopped garlic and cook for about 30 seconds until fragrant. Add the onions, mushrooms, and chili, and stir-fry for 2–3 minutes until the onions start to soften.

Add Optional Broccoli: If using, add the broccoli florets and stir-fry for another 2 minutes until they are bright green but still crisp.

Combine Everything: Return the cooked beef or pork to the skillet. Pour in the prepared oyster sauce mixture and toss everything to coat. Stir-fry for another 1–2 minutes, letting the sauce thicken slightly and coat all the ingredients.

Add Green Onions and Serve: Add the green onions and give everything a final stir. Serve hot with rice, and garnish with extra sliced chili if desired.