Store unripe avocados at room temperature in a brown paper bag to speed up maturation. To remove the seeds from avocado halves, cut down the length of the avocado in a continuous line from the stalk end to produce two halves. Hold the half containing the seed in the palm of one hand, then tap a sharp knife into the seed and twist slowly to remove it. To remove the skin, use a small knife to pull the skin away from the stalk end: it should come off easily if the avocado is ripe, although with some varieties the skin breaks at random, making this a fiddly process. If only one half is required, store the other with the stone still attached [sealed in plastic film] as this technique inhibits discolouration.