Tvorog

Tvorog is one of the most ancient and popular Russian dishes.
It was known in ancient Rome too, and one of philosophers, Columella, said that it is a favorable dish on a rich and poor table.
Tvorog is a well-balanced and useful dish, containing proteins, necessary amino acids, microelements, and vitamins. It is allowed-for-all dish, and it is absolutely necessary for children, because it contains plenty of calcium, and 14%-22% of protein. For a long time, Russians called tvorog "syr", which means "cheese", and even still pancakes with tvorog are named "syrnik".
People in villages, who had cows, eat tvorog and dishes containing tvorog, almost daily.
The sour milk, where proteins have already curdled, was product for preparing of tvorog.
Pour sour milk into an oven-safe dish (in old times – large pot), and place the dish into a not very hot oven (traditionally – in Russian oven).
After a few hours, take the dish off from oven, and pour its contents into fabric bag.
Place fabric bag in a colander, and let buttermilk to stream down.
After that, put press (any clean heavy staff) on the bag.
Tvorog left in the bag.
You can eat it with salt, sugar, and sour cream, or use it in different dishes.
The only disadvantage of this tvorog is that you cannot keep it more than 3 days in a refrigerator, or it will turn sour.
To prolong its storage time, you have to dry it.

The technology of draining tvorog is next:

Place fresh tvorog (after pressing) in an oven-safe dish, and put the dish in a not very hot oven once more, and put under press in a fabric bag once more.
After 2-3 times, you will have very dry, crumbly tvorog.

To keep it for a long time (up to half a year), put it in a clean pot, pour melted butter (Russian style) over it, and keep in a cold dry place under a tight lid. People took such tvorog on long trips.
Peasants traded with such tvorog, and the dryer the tvorog, the more expensive it was.
Modern technologies of tvorog preparation are not far from ancient ones:

Ingredients:

¼ h whole milk
1 cup plain yogurt

Method:

Boil milk in glass or enameled saucepan. Add yogurt, and mix.
Turn off heating, and let sit. After it turns warm and curdles, put any uncolored clean fabric bag in the colander, and pour the semi-finished product into a bag. Let drain. That means let the buttermilk stream down.
To make dryer tvorog, place a press over it.
Tvorog is ready.

Note:

Hundreds of recipes using tvorog are in Russian cuisine.
The most famous dishes from tvorog are "syrnik", "vareniki with tvorog", melted cheese, "zapekanka", "cheese balls with potato", or "cheese-potato cakes", and "Paskha" – Easter cake.
I will give these recipes later.