First of all drain the black beans and rinse them under cold running water. Now place half of them in the goblet of a food processor, then add the tomatoes, jalapeno peppers, lime juice and coriander. Season well with some salt and whiz the whole lot until it is quite smooth.
Next add the rest of the black beans and give these a short burst in the processor (this is to give the dip a little bit of texture). Now transfer it all to a bowl and fold in the crème fraiche.
Taste to check the seasoning, then serve garnished with some more coriander and wedges of lime, with potato wedge (or whatever else you fancy) to dip in.