In a small bowl, whisk together stock, soy sauce, cornstarch, mirin, and chile paste. Place 1/2 cup mixture in a small bowl. Add tofu, and let sit at room temperature for 30 minutes. Reserve remaining sauce. Fill a large bowl with ice water, and set aside.
Bring a large pot of water to a boil. If using baby bok choy, cut into quarters lengthwise; for regular bok choy cut into 1-inch dice. Cook for 2 minutes in boiling water. With a slotted spoon, transfer to ice water to cool. Remove from ice water, and set aside. In same pot, cook broccoli florets for 1 minute. Transfer to ice water to cool. Remove to bowl with bok choy. Set aside.
Drain tofu, reserving sauce. Spray a wok or large skillet with cooking spray, and heat over medium heat. Add carrots and mushrooms. Cook for 3 minutes, stirring frequently. Add tofu, bok choy, broccoli, water chestnuts, baby corn, and garlic. Cook for 1 to 2 minutes. Add reserved sauce, and cook, stirring until it thickens. Serve immediately.