Cut off joi choi leaves. Soak shiitake mushrooms, cut off the stems and cut into 6 pieces each. Drain mushroom tops and cut in half. Slice bamboo shoots.
Heat 1 tablespoon of oil in a pan and add the bok choy stems for about 1 minute, then add leaves. Saute lightly. Add 1/2 cup broth and cook until tender. In a separate pan heat 1 tablespoon oil. Add scallops, shiitake, button mushrooms and bamboo shoots. Saute lightly. Add 1 cup broth and cook on low heat for 5 minutes.
Remove vegetables/scallops from pans and arrange attractively on a serving platter. Set aside.
Add 1/2 teaspoon salt to broth in which the vegetables and scallops were cooked and make gravy, thickened with 1 1/2 teaspoon cornstarch (mixed with water) and pour over vegetables and scallops.