Avocados are extremely prone to discolouring, once cut. This does not affect the flavour, but its appearance will suffer. You can rub some lemon juice over the surface to help preserve its ripe green colour. To half an avocado, usually to be filled, simply slice it in half, then twist the two parts free and remove the stone. To peel an avocado, use either a sharp knife or potato peeler, depending on its ripeness. Avocados may come to your door before they are ripe. If you want to prolong their ripening, then keep them in your fridge. However if you need them to ripen quickly then leave them in your kitchen or larder. If you hold the avocado in your hand and apply light pressure, it should give slightly if it is ripe. Suitable for home freezing.