This is a very special vegetable, rare in Canton, rare even in Hong Kong. It is a Shanghai product (available widely in the United States) and prepared in a simple manner that emphasizes its distinctive taste.
Remove old, discolored outer leaves of bok choy, trim stems, cut each head lengthwise into quarters. Remove most of leaves. Wash bok choy well under running water to remove sand and dirt. Drain.
Heat 6cups water in a wok; add baking soda and salt. When water boils, ad