The yoghurt that you will use as a starter should be fresh and at room temperature for best results. If the yoghurt you have is watery, place it in a muslin cloth and let it drain for an hour or so in order to have a thick consistency.
Pour the milk into your bowl/pot. I prefer using a heatproof bowl like the one shown in the picture.
Place the bowl/pot on low heat and gradually bring it to a slow simmer. Make sure the milk doesn't boil over, keep the heat constantly on low and stir every now and then. Once it starts to boil, let it simmer for about 5 minutes, then turn off the heat. Leave the pot/bowl where it is and let it sit for about an hour. It needs to come to a temperature which is hot but not burning-hot, about 110 C if you have a kitchen thermometer.. You should be able to stick a finger into the milk and feel the heat without getting burnt.
It is highly recommended to let the yoghurt set in the same bowl/pot that you boiled the milk in. Transferring it at this point might not give you the best results.
Pour 1 tbsp. of the fresh yoghurt/starter into the bowl, then using a whisk or fork, whip it well into the milk until it is nice and frothy. Take the 2nd tbsp. of yoghurt and rub it all around the inside of the bowl where the edges of the milk touch the bowl. Yoghurt starts to form from the edges, so this helps to speed the process along.
Cover and put your dish in a warm area, like in the oven with the light on (for a bit of extra warmth) or in the microwave. Let it sit for about 6-8 hours...preferably overnight. Don't shake it, don't move it, and don’t touch it. Just put it in there and forget all about it for the recommended hours.
Check the yoghurt, if it looks solid and ready, put it in the refrigerator and let it cool for around 4 hours before serving. If it's still not solid when you check on it, give it a few more hours before refrigerating.
Serve your yummy, beautifully & luscious home-made yoghurt!!