Thaw tofu until it comes to room temperature, about 2 hours. Squeeze between paper towels to drain thoroughly and transfer to a bowl. Add Worcestershire sauce, then enough soy sauce to cover. Let marinate, at least 1 hour.
Drain tofu, discarding marinade.
Heat a wok or large skillet over high heat until smoking, about 30 seconds. Add oil; heat until shimmering, about 20 seconds. Add green onions and garlic; cook and stir until fragrant, about 45 seconds. Add tofu; stir-fry until scrambled and heated through, 1 to 2 minutes.
Cook yellow onion in the wok until softened, 2 to 3 minutes. Add frozen vegetables; saute until heated through, 2 to 3 minutes. Stir in rice, mirin, sesame oil, and enough soy sauce to cover the rice. Season with salt and pepper. Add bean sprouts; cook and stir until rice is hot, 1 to 2 minutes.
