Marinate Proteins: In a bowl, combine chicken, beef, and shrimp with 1 tablespoon soy sauce and 1 tablespoon cornstarch. Set aside for 15 minutes.
Prepare Vegetables: Blanch broccoli, carrots, and snow peas in boiling water for 2 minutes. Drain and set aside.
Heat the Wok: Add vegetable oil to the wok and heat over medium-high.
Cook Meats: Add marinated meats to the wok and stir-fry until browned and cooked through. Remove and set aside.
Sauté Vegetables: In the same wok, add garlic and onions, cooking until aromatic. Add bell pepper, baby corn, and blanched vegetables. Stir-fry for about 3-4 minutes.
Combine and Simmer: Return cooked meats to the wok. Mix in chicken broth, remaining soy sauce, oyster sauce, and sesame oil. Bring to a simmer.
Thicken Sauce: Dissolve remaining cornstarch in a little water and stir into the wok. Cook until the sauce thickens.
Season and Serve: Adjust the seasoning with salt and pepper to taste. Enjoy it warm, served alongside steamed rice or noodles.