1/2 l of soya milk
1/2 of soya yoghurt or milk yoghurt.
Mix the soya milk with yoghurt into a bowl.
Place the bowl in a pan full of water and heat the pan until reaching a temperature of 50°C. (I did it with finger testing…not too hot not too cold…)
Stop the heating and hermetically seal the bowl of milk.
Set aside during a few hours.