Q: my local Tesco extra (which is huge!!) has devoted almost an entire area in its "passover" section to picked cucumber!!.... why?
A: There is no particular significance to pickled cucumbers on Passover whatsoever. That having been said, there is indeed significance to having something sour on this holiday. Perhaps not many people are aware of the fact that the Karaites misinterpreted the Hebrew word for leaven (hametz) and thought it meant that they must refrain from eating sour foods during this festival. To show that we are not Karaites and do not misunderstand the commandments, we DO eat a sour food. This is often borscht, but it could just as well be a sour pickle.