1) Bring 600ml (1 pint or 2.5 cups) milk to the boil and hold for about 5 seconds. Let it cool down to 43C /110F, just above body temperature, so that it feels comfortable when tested with a clean finger.

2) Pour the milk into a flask. Stir in 2 tablespoons live yogurt. Screw the top on the flask and leave to thicken. This will take about 3-8 hours.

3) Refrigerate as soon as thickened but do not shake as this causes curds to form. Mix with honey or fruit for extra flavor if liked.
Alternatively use an electric yogurt maker, complete with thermostatically controlled temperature gauge and serving pots, according to the manufacturer's instructions.