I have the hardest time believing that the sauce is this simple, because it has a layered complexity of favor- for me.(maybe that’s the effect of roasted soybeans instead of the chinese fermented black beans that one normally thinks of when they hear ‘black beans’ in asian cooking.) You don’t use chicken stock instead of water? and no scallions or ginger? Does packaged black bean paste contain MSG or hydrolized yeast extract?
Two comments: *your knife technique is admirable! but i do hope you will change your potato chopping technique; you need to have a flat side down always, of any vegetable, before you beging slicing, so cut off a little slice of the rounded potato to make it flat, or halve it, and place it cut-side down, like you do your cabbage. and * do you usually do this in a wok? it seems that the char possible in a wok- would add a lot of good flavor to the dish.

Thanks again, arie; what you have created here is so very helpful!
best,
mindy