If you've got an oriental supermarket near you it's actually pretty easy to make your own black bean sauce from fresh. It's also pretty easy to stuff up but still well worth a go IMO (it needs to be freshly made and you need to get the balance right to taste the best).

Ingredients (for 2):

500g / 1lb of thinly sliced chicken, thinly beef or prawns. If you want something a bit more 'fancy' then try it with scallops.

1 diced onion

1 diced red or green pepper (mixed looks nicer but 2 peppers is a bit too much for 2 people IMO)

2 or 3 cloves of garlic (crushed or *very* thinly sliced - i.e. almost transparent)

1 small piece (0.5 to 1 cm) of fresh root ginger - chop off the skin then finely grate it.

2-3 small green chillis (thinly sliced with seeds in or very finely diced)

about 1 (flat) tablespoon of black beans (soak them in warm water for 5 mins then drain and crush them - but not to a paste - they sometimes have gritty bits in them that you want to remove and you want to release the flavour too)

1 tablespoon of soy sauce (dark soy sauce)
1 tablespoon of dry sherry (or proper rice wine if you have it)

Easy way:

Gently stir fry the garlic and ginger. Turn up the heat and stir fry the meat for 2-3 mins until cooked (longer if you haven't sliced it that thinly!). Add the onions and stir fry for 1 minute then add the pepper and fry for a further minute. Now add the black beans, sherry (or rice wine), soy sauce and chillies and fry off for a further minute or two. If you want more of a 'wet' dish (more sauce that is) add a bit (tablespoon or two) of water. If you want to thicken the sauce mix a *small* amount of cornflour into the water (use cold water) before adding it to the sauce. The corn flour dilutes the flavour quite a bit if you use too much.

Real proper way:

As above but fry the meat first and veg first (without any of the spices - not even the garlic or ginger) then take it out of the pan (keep it somewhere it won't get cold) then do the sauce and finally add the meat and veg back in. Makes it taste 'fresher'.

Can sometimes work well if you let the meat marinade in the black beans / soy sauce / sherry but it's easy to get a very salty / strong tasting meal that way too.