Break up a left-over chicken carcass into bits or chop 2 chicken pieces into chunks, bones and all. Stick the bits in a largish saucepan, add around 2-litres of water and give it a good salting. Bring to a bubble and spoon off any gunky stuff that floats to the top, then sling in 5 cm peeled and thickly sliced fresh root ginger and 5 halved and chopped fat spring onions. Turn down the heat and leave to bubble gently for about 1 hour. Strain the stock and discard all the bones and bits.