Directions

1. Make the sauce: In a medium bowl, combine soy sauce, vinegar, ginger, sugar, and sesame oil. Stir until sugar dissolves; set aside.
2. Steam the bok choy; bring 2 inches of water to a boil in a large straight-sided skillet or stockpot. Arrange bok choy in a single layer in a steamer, and place over simmering water. Cover, and steam until hot and tender when pierced with the tip of a knife, 4 to 5 minutes.
3. Cook the tofu: Heat a large nonstick skillet or a wok over high heat. Add oil, and swirl just to coat bottom of pan. Pat tofu dry, and arrange in pan in a single layer. Cook for 2 minutes. Turn, season with salt and pepper, and cook for 2 minutes more.
4. Transfer tofu to a serving platter. Pour sauce over tofu, and top with cilantro, scallions, and serrano pepper. Serve with steamed bok choy and rice on the side.