First you need to get yogurt with active bacteria cultures. It will be listed as an ingredient. I used Activia. It also happened to be raspberry since I didn't have plain yogurt. The recipe calls for 1/4 cup of yogurt and 1/2 gallon of milk. You can use any type of milk (even soy milk). I used 1.3 L of 1% milk from the store (one bag as we buy it here).
Warm up the milk to just below a boil. Let it cool until it is still warm but not too warm. It should be about the temperature of water you would start bread yeast at so about 110 - 115 degrees F is recommended. Stir in the store-bought yogurt (or yogurt from previous batch of home-made) and let this sit covered with a towel. Leave it over night in a warm place.
I had put this in my oven when it was still slightly warm after making bread. I later decided to clean my oven and nearly cooked my yogurt to death! After the mad scramble to get my yogurt out of the oven set to self-clean, I let my yogurt sit on top of the stove while the oven was being cleaned. I put the pot on my spoon holder so it wouldn't get any direct heat as the top of my stove got pretty warm.
In the morning I woke up to yogurt. It's hard to see but if you look around the edges you can tell the milk has solidified and is pulling away as I tilt the pot.
See the slight ripple on the surface?
You can eat the yogurt as is if you like runnier yogurt (like regular store-bought yogurt). I prefer Greek style yogurt and I had a mesh bag from jam making so I drained my yogurt for a couple hours. You can use a cheese cloth, clean pillow case, anything that will let the moisture seep out while holding back the solids. Keep the whey that drains off the yogurt for making bread.
Over time you will get quite a bit of moisture come off your yogurt and it will then settle and separate. I kept the whey in the fridge (for about a week) and just recently used it up making bagels, buns, and sourdough bread. Refrigerate the yogurt when you get the thickness you want.
Now to make the curd to go with the yogurt. Set up a double boiler. The bottom has a pot with a couple inches of water. Keep an eye on the water below, check every so often to be sure it isn't boiling like crazy and you definitely don't want to run out of water. It should be a nice rolling boil.
The top has a heat safe bowl. For the curd I followed the recipe in the book. Equal parts (1/2 cup) lemon juice and sugar plus 3 eggs. The recipe calls for fresh lemon juice and zest. I used bottled and it was good. Whisk this constantly. It will thicken and lighten in colour.
Get ready to strain your curd so it is nice and smooth. I strained into a measuring cup because I wanted to put a curd layer in the bottom of serving bowls and put yogurt on top. The measuring cup has a spout for easy pouring.
Once your curd has stopped thickening, cook for several more minutes to be sure the eggs are cooked and then strain the curd.
Pour into waiting bowls, cover and refrigerate until completely cooled. If you don't have bowls with lids use plastic wrap and place the plastic wrap right on the surface of the curd before cooling to avoid having a skin form.
Once your curd and yogurt have chilled completely you can assemble your yogurt pots (or eat now). I hadn't stir my yogurt at all at this point so it appears lumpy.
Once you stir the yogurt it gets smooth and creamy. Don't mind the raspberry seeds.
See how smooth and rich these look? They are not very rich as all but they do have a creamy texture and very mild tang.
The curd was very tart and slightly sweet. It was very nice. I found that about 1/3 curd to 2/3 yogurt was nice. Phoenix liked more yogurt and less lemon. Play around and find your perfect mix. I also liked to dig to the bottom with every spoonful to get just a bit of curd and mostly yogurt on every bite but Phoenix liked his mixed up.
This experiment was very satisfying! I have very small canning jars that I put the rest of the curd and yogurt in and have been sending them to school in Phoenix's lunch. We have been eating them for breakfast and snacks as well. This recipe would have made 8 of these small sized jars. I ended up splitting the ones I made at first in half as it was too big of a serving for one person unless you REALLY like lemon yogurt.
Also, if you like how your yogurt went, be sure to keep back 1/4 cup (or one pot) to make the next batch. Your yogurt should keep for about a week in the fridge.