Last spring I started making my own yogurt. Then by fall, I got tired of it. It took too much time, I eat a ton of it, and I was always having to make another batch at some inconvenient time. So I started buying it again. That's when it occurred to me that the solution was not to stop making yogurt, but to make bigger batches. Duh. The cost/benefit ratio only gets more favorable, besides not having a zillion little pint-sized plastic things around to throw away. Like 2 or 3 a week!
I posted a very similar set of instuction on facebook a while ago, but my procedure has evolved slightly since then. At any rate, here it is. Keep in mind, I make greek-style strained yogurt.
Buy an 8oz thing of Fage brand plain yogurt.
Buy 1 gallon of milk. I get a half each of whole and 2%. More fat = good. Low fat foods just do not satisfy you, and what's worse, will encourage you to overeat cus hey, it's low fat! Full fat foods make you happy, and more happy = good. Nuff said.
Here is my equipment list:
a whisk- you will need these 2 things the first day.
the next day ( or possibly later the same day) you will need:
A big pot with a lid to boil the heck out of anything that is going to touch your yogurt OR a dishwasher. I boil things.
A couple clean spoons or spatulas
A pair of tongs is useful for grabbing hot things out of boiling water.
A large wire colander. Mine is about 14" across and almost 9" deep.
A circle of muslin big enough to line the colander and have a little extra wiggle room
A small glass jar with a lid to keep a bit of yogurt as starter for your next batch. That way you don't have to buy more brand-name yogurt, which effectively doubles the cost of making your own.
The third (or maybe second) day you will need storage containers to hold a half gallon of greek yogurt.
Leave the milk and yogurt on the counter to start warming up. You can put the yogurt container in a little dish of warm water to get it woken up, it seems to speed up the process.
Put about 3 cups of water and the whisk into the stockpot, put on the lid and boil it for about 5 minutes. This sterilizes it. Set the whisk aside somewhere clean, dump out all the water and put in the milk. Gently heat the milk to somewhere between 90 and 100 degrees. You don't want to burn it or shock the starter when you add it. Once the milk is up to temp, whisk in the bought yogurt, put on the lid and leave it alone.
The important thing is to keep it warm for the next 8 to 12 hours. I turn on my oven light, boil a kettle of water, then put the yogurt pot and the kettle together into the oven. Between the bulb being on and the hot kettle, this works beautifully. It will not do anything at all for a good 8 hours! Do not keep fiddling with it, it will get germy and fail to keep well.
After about 8 hours, peek at it. If it smells yogurty and appears to have curdled, it's done. If it doesn't, stir it well ONCE with a clean spoon, put the lid back on and go away for a few more hours. Don't worry if it seems to be taking a long time, I've had batches that took almost 24 hours, and some as few as 8. Depending on how much time you have, once it curdles, you can either stick it in the fridge and wait till the next day, or go right on to the next step:
Put the small glass jar, its lid, and the cloth circle into a big pot with a couple cups of water. Boil/steam the heck out of them for 5-10 minutes, then dump out the water. Fill the little jar with some of your starter. If you have any left (I always forget to save some), add a bit of fresh milk so the starter will have some food. Put that in the back of the fridge til next time. Then line the colander with the cloth, put the whole business over the big pot, and pour the yogurt into it. The more curdled bits will have settled to the bottom, scoop them out too. Cover the colander and put the whole thing in the fridge for 24 hours. By that time enough whey will have drained out that it will be about as thick as sour cream. You can leave it longer and it will get almost as thick as cream cheese, but that's up to you. Put it in storage containers and that's it!
Now, what if you don't want greek yogurt? What if you want little lunch-sized things of regular yogurt? Well, that's where a dishwasher would be real handy. Here's what I suggest. Use a different starter- stonyfield, brown cow, whatever, as long as it has active bacterial cultures in it. Do the first step, and while you're gently heating the milk to add the starter, run the dishwasher with enough little jars and lids to hold your whole batch. That's like, 16. Put the yogurt mix straight into the clean jars, put on the lids, and incubate them the same way as above. Don't be tempted to shake them around though, you'll wreck the texture. You'll be able to see when they've set, and then you're done!