"The ferraúra have to have a bright green colour, but not too intense," she tells me, referring to the horseshoe-shaped beans that are almost spilling out of their crate. The rochet, a red and green bean, "has to be a few centimetres wider and thicker, but only a little bit". And as for butterbeans, which I can see bulging through their cases, "the best (ones) to eat are when they begin to turn from yellow to green".