I use a yogurt maker that you can buy from Lakeland by mail order. I have never tried making it with unsweetened soya milk which is what I use for my cinnamon porridge, but it might work. I make it with skimmed milk and 2 tbspns of Marvel or similar skimmed milk powder and set it to "yog" overnight and you get loads from the recipe leaflet that comes with it. You need a live yogurt starter, I use Yeo Valley but any live plain yogurt will do. I put two handfuls of frozen berry fruits in the microwave for 90 seconds or so, and three good tablespoons of my yogurt over it. It is really satisfying.