einlegen is a German word which means "to pickle" or " to marinate" , example to make a pickle or to pickle fruits, vegetables or meats.
sauer einlegen is also defined as "to pickle", using sour products like vinegar to make for example pickled cucumbers
in Salzwasser einlegen is a German term which means "to brine" or to pickle in brine, example is to brine fish
The Glossary about the World of Food !