Out of curiosity, I just searched Taobao, China and the world's largest online shopping portal, for bouillon cubes. Not a one to be had. The only thing that came close is these Knorr (家樂 - Cantonese: gaa1 lok6) jellified stock concentrates (what are these things actually called in English?) They come in 'old layer chicken flavour' (pictured) and 'pork bone flavour'.
Cubes certainly were available a few years back, but as I said before, were far from mainstream. Now they seem to have gone completely. I only ever bought the clam flavour they used to have.
* Curiously, if you add a 福 to Knorr's Chinese name, you get the Sinicized name of French supermarket chain, Carrefour (gaa1 lok6 fuk1)
