Dilute the jelly bag with hot water until the grains completely dissolve. Most importantly, the water should be two times less than indicated on the package.
Let it cool down a little.
Add sour cream to the jelly.
Beat with a mixer for five minutes so that the jelly is soaked with bubbles.
Pour the cream into the molds and put it in the refrigerator.
After an hour, take it out and enjoy.
