Feeling some heartache for the all night electrical consumption of the yoghurt maker, I decided to experiment with making yoghurt in the thermal pot. I was surprised how EASY it is!
Scald 400ml of milk gently. This means that you bring it to a very gentle boil. Keep stirring so that the milk does not boil over nor burn at the bottom of the pot. Keep it gently boiling for at least 10 minutes. This will remove the oxygen from the milk. This allows the yoghurt bacteria to work better. Yoghurt bacteria are anaerobic. They work better in the absence of oxygen. Too much oxygen in the milk leads to less firm and less creamy yoghurt.
Cool the milk down on the countertop. When it reaches about 80 Deg C, spoon out 100 ml of milk into a small mixing bowl. Stir in 100ml of yoghurt into the mixing bowl. When the mixture is smooth and all lumps have been removed, pour the mixture back into the thermal pot. Insert the thermal pot into its insulator.
Make sure your thermometer and all other utensils you now introduce into the milk are well sterilised. You don't want harmful bacteria growing in your yoghurt culture.
I don't use a thermometer. I just feel the sides of the pot. If it feels almost hot enough to hurt but does not, that is the right temperature. Then again, my skin could be tougher or more sensitive than yours. Hence, if unsure, use a thermometer.
After 15 hours of incubation, open the thermal pot. Voilà! Yoghurt! Of course, you can add sugar and flavouring into the milk before you culture the yoghurt. I make plain yoghurt. Members of the family who want flavouring will just stir in jam. I like to stir in lemon curd to get lemon flavoured yoghurt.