Lactose intolerance is a cruel mistress. While non-dairy yogurts are easy enough to find, they are terribly expensive and oftentimes the ingredients list has much to be desired. Fortunately, yogurt of any kind is not hard at all to make. All you need is milk of some type, yogurt or yogurt starter, and a warm place for the yogurt to ferment. Also, it is terribly important to be as clean as possible. Sterilize all utensils and containers. You are essentially trying to create an atmosphere to grow bacteria. You don't want to introduce the wrong types. Sterilization can be done a number of ways, I prefer to use my dishwasher or oven. (To use an oven to sterilize utensils, preheat to 225° put everything on a baking sheet, and let it "cook" for 7-10 minutes. I usually do this a little while before I start to give everything time to cool down a bit.)
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Step 1: Prepare Yogurt for Fermentation
For this recipe, I used four cups of organic soymilk and about 1/3 a cup of starter from my last batch. Heat the milk to between 107° and 113°. Use a thermometer to make sure you get the temperature exactly right. To cold or hot, and the yogurt will either not ferment or the bacteria in the starter will die. Once your temperature is right, stir in the yogurt starter. Pour everything into a sterile container with a lid. I like this Pyrex because its easy to oven sterilize and I can leave the thermometer sticking out to monitor the temperature while the yogurt ferments.
Step 2: Tuck It Into Bed!!
Well, not really. What you need now is a warm place that can be undisturbed for 5-6 hours. I like to use a heating pad to do this. Put the heating pad on the counter, set it to low, put a folded over towel on top of it. Put the bowl of yogurt on the heating pad/towel, and cover the whole thing up with another towel. Monitoring the temperature is not a bad idea, although in my experience, this should keep the temperature about 110° which is about perfect. Once 5 or 6 hours pass, the yogurt should be thickened. I like to go ahead and put about 1/3 cup of yogurt in a very clean jar at this point so I have starter ready to go for my next batch. Put it in the fridge and it should last at least a week. A little water forming around the edges of the yogurt is totally normal. Either pour it off or stir it back up.
Step 3: After 5-6 Hours
Yogurt is done at this point. ( don't worry about the air bubbles, that's from mixing.) Foolproof, cheap, and simple! Put it in the fridge and enjoy. Please keep in mind that since this is soy yogurt, it will be a bit thinner than dairy yogurt. This leads to the next and optional step.
Step 4: Straining Out the Liquid
Yogurt is yogurt. Anyone who tells you different is lying. If you prefer a thicker, Greek style yogurt, just strain the liquid out. I like to line a colander with coffee filters and put it in a bowl with at least an inch clearance. Cover the whole contraption with plastic wrap and let it sit several hours or overnight. You can even repeat this step to get more water out if you choose. You now have "Greek style" yogurt.