Prepare the sauce:
In a small bowl, mix the soy sauce, oyster sauce, cornstarch, sugar, chicken broth, and sesame oil until smooth. Set aside.
Cook the protein:
Heat 1 tbsp of vegetable oil in a large wok or skillet over medium-high heat. Add the sliced meat or shrimp and stir-fry until cooked through. Remove from the pan and set aside.
Stir-fry the vegetables:
Add the remaining 1 tbsp of oil to the pan. Stir-fry the onion and garlic until fragrant. Add the carrots, celery, and any firm vegetables, cooking for 2–3 minutes. Then, add softer vegetables like bok choy, bell peppers, and mushrooms. Stir-fry for another 2–3 minutes until the veggies are tender but crisp.
Combine the ingredients:
Return the cooked protein to the pan and toss with the vegetables. Pour the sauce over the mixture, stirring well to coat everything evenly.
Simmer:
Allow the sauce to simmer for 1–2 minutes until it thickens and everything is heated through.
Add bean sprouts:
Stir in the bean sprouts and cook for 30 seconds to 1 minute for added crunch.
Serve:
Remove from heat and serve hot over steamed rice or noodles.