Combine hot water and dried mushrooms, and let stand 20 minutes. Drain the mushrooms through a sieve over a bowl, and reserve the soaking liquid and mushrooms.
Cook noodles in boiling water 3 minutes, omitting salt and fat, and drain. Return noodles to pot. Add reserved soaking liquid, soy sauce, and pepper; bring to a boil, and cook 8 minutes or until the soaking liquid is absorbed. Stir in the reserved porcini mushrooms.
Heat sesame oil in a wok or large nonstick skillet. Add tofu, lemon grass, ginger, and garlic, and stir-fry 30 seconds. Add zucchini, button mushrooms, and shiitake mushrooms, and stir-fry 2 minutes. Add bok choy, and stir-fry 3 minutes or until wilted.
Divide noodle mixture evenly among 4 shallow bowls, and top with zucchini mixture. Sprinkle with cilantro.