You can't buy it anymore as La Choy stopped making it years ago. But you can make it at home. This recipe comes from La Choy: Mix 1 teaspoon of soy sauce in 1/2 cup of dark corn syrup. Haven't tried this yet but thought I'd share the link... Dynasty brand bead molasses http://spicesgalore.stores.yahoo.net/dybemo.html
Wash and chop the bok choy into 1 inch pieces. Heat some peanut oil in a wok or fry pan. Add a little minced garlic and ginger. Saute for about 30 seconds. Toss in the bok choy and saute until it is tender. Add a couple of tablespoons of soy sauce and a few drops of sesame oil. This is the simplest I've tried but there are many others.
Sure, they are both soy sauce. Tamari is a grade above shoyu (soy sauce). They are both made by fermenting soy beans, shoyu has a mix of soy and wheat. Some Japanese brands are thick and dark like tamari. Tamari is typically thicker and darker and some brands have no wheat. Some brands of Chinese soy sauce add molasses to thicken and sweeten it.