1. Cut the chicken breast into shreds approximately 1 inch long and 1/8 inch wide.
2. Steam the shiitake for 1 minute in an Oriental steamer or in the improvised steamer. Remove from the pot and shred the mushrooms as fine as possible while they are still hot.
3. Drain the rice and combine it with the dashi, mirin, salt, a few sprinkles of MSG and the soy sauce in a 3- to 4-quart pot. Add the gobo and shiitake, then the chicken. Bring to a boil over high heat, stir once or twice and cover tightly.
4. Reduce the heat to moderate and cook for 3 minutes, then lower the heat again and simmer about 4 minutes longer. Turn off the heat, and let the tori gohan rest covered for 2 minutes before serving.
5. Divide equally among 4 serving bowls and garnish each portion with a sprinkling of the chopped parsley.
6. Serve as a luncheon dish, accompanied perhaps by miso soup and bottled Japanese pickles; or serve in smaller portions at the end of a 5- or 7-course Japanese dinner.
7. Shredded uncooked shrimp, clams or lobster may be substituted for the chicken and cooked in precisely the same fashion.
