Black Soy Sauce, differs from regular soy sauce because of its sweet flavor. It's known by a few different names, such as Sweet Soy Sauce, Dark Soy Sauce, Thick Soy Sauce, etc. As you can guess the sauce itself is dark, thick, and tastes a little sweet. A little of this sauce goes a long way in the dishes that you prepare.
This brand is called "dragon-fly" and you will have to get this at an Asian food store, or online here.
Sauces 
Black Soy Sauce, differs from regular soy sauce because of its sweet flavor. It's known by a few different names, such as Sweet Soy Sauce, Dark Soy Sauce, Thick Soy Sauce, etc. As you can guess the sauce itself is dark, thick, and tastes a little sweet. A little of this sauce goes a long way in the dishes that you prepare.