I've been using this in more and more recipes lately so figured I'd share how it's made. It's my favorite kind of yogurt to date!
Creamy Peanut Milk Yogurt
Soak half a cup of plain, raw peanuts overnight. Grind them into a fine paste with some fresh water (the soaking water should be thrown out).
Transfer to a large pot, add lots of water (about 2 1/2 litres), bring to a boil, reduce the heat to medium and continue to simmer for about 30-40 minutes (stir once in a while). Once it has cooled down to room temperature, strain through a fine sieve. The peanut milk is ready! (The peanut grounds left in the sieve can be used in soups and curries or kneaded into chapathi or bread dough).
Heat the milk to a lukewarm temperature, add a wee bit (just 1-2 tsp will do) of soy yogurt and stir it in lightly with your fingers to introduce the cultures.
Cover and keep aside in a warm spot (a turned off oven or microwave is a great place!) and in about 6-8 hours, you'll have thick, creamy peanut yogurt. :)
It can be stored in the fridge for at least one week (maybe more but it's never lasted that long at our home because we finish it up really quickly! LOL). As the days go by, it gets even thicker and creamier.
A note about Starters:
While making vegan yogurt, if you don't have soy yogurt on hand to use as a starter, then take half a cup of soy milk, heat it to lukewarm, squeeze in a little bit of fresh lime/lemon juice, stir and keep aside. This will turn into yogurt after 6-8 hours but the texture isn't perfect. That's why you make this yogurt in a small quantity and then use that as a starter to make more vegan yogurt. Always make sure to save a few spoonfuls of yogurt in every batch to use as a starter for the next batch. I've noticed that when an old line of starter is used like this for 'generations', the texture and taste of the yogurt gets more delicious over time.
Alternately, you can also use rejeuvelac made out of soaked wheat berries.
I have also tried using chilli crowns as a starter as described on Tongue Ticklers and that worked well too.
Update on 23rd April 2013: New blog post showing the step by step process of making peanut curds using Howdo.