i've been making yogurt for almost two years now, and have never had two batches turn out exactly the same. i never mind this though, because they are always good. i always feel like heidi when i make yogurt.
it is simple to make and easy to customize to your likes. i am a super-sour plain yogurt lover (think nancy's), but most people aren't. i have never been able to get my homemade yogurt to be quite as sour as i would like, but i'm not complaining. its delicious by itself right out of the jar, with honey, granola, fresh fruit, in smoothies or in tsatsiki sauce!
all you need is:
one or two tablespoons of plain yogurt
about a pint of milk or half & half (i like the thickness of half & half)
a clean mason jar with a lid.
you can heat the milk if you want, but its not necessary. if you do heat it, its best to keep a thermometer in and keep a very close eye on the temp. turn heat off around 110 degrees to preserve a bit more of the enzymes in the milk, but do not let it get above 180 degrees or it will burn.
i rarely even heat my milk anymore, just pour it straight cold into the jar, along with the tablespoon or two of yogurt. i do a quick stir and put the lid on the jar.
leave the jar in a warm place for 12 to 48 hours. i am lucky enough to have a spot warmed by a pilot light to culture my yogurt, which may speed up the process a little. try the inside of your stove or the top of the fridge. as it cultures i will often tilt the jar to gauge thickness and give it a sniff to test for sourness. to be honest i haven't noticed a huge difference between a jar left for 12 hours vs. 48 hours, have fun experimenting.
the yogurt will firm up even more in the fridge, so let it rest in the fridge for at least 8 hours before you eat it.
i have used nonfat and whole milk to make yogurt before, but its hard to get the thickness i like. you can add a few tablespoons of nonfat milk powder to your mix to thicken it up if you are looking for a lower fat version of this and using a watery milk.
this recipe can also be used to make sour cream or cream fraiche by using a tablespoon or two of either as the starter culture instead of yogurt. instructions are the same. sour cream is so good in soups, casseroles, baking, tacos, etc...
what i have learned about making yogurt is that it is easily adaptable, not too finicky about exact measurements or times. it is fun to experiment with, and you can always start a new jar with the last spoonful of yogurt from the previous batch. if you like a sweeter yogurt add some maple syrup, honey, or fruit jam to the finished yogurt after it has set in the fridge. i love a drizzle of maple syrup on yogurt.