
Re: Rollmops
Make it yourself. Like most peasant food, it's not exactly rocket science, and homemade is always better than bland, homogenized store-bought versions. There are a zillion recipes online. Or ask your grandmother/great aunt.
If you can't get fresh herring (or other suitable fish) to salt for yourself, you can purchase them online, already salted and ready for the pickle/dressing.
You mention storage ... The homemade version isn't suitable for storage (five days in the pickle, eat within five days after that), unless you have a pressure canner and know how to use it with fish.
Beer, because nothing washes down pickled fish better than beer :-)