It became a nationwide pantry staple almost by accident — Soviet planners pushed kelp harvesting hard in the mid-20th century for its iodine content, and pickled kelp salad ended up on tables from Vladivostok to Kaliningrad.
Morskaya kapusta is shredded kelp seaweed marinated with vinegar, oil, onion, and carrot into a tangy, crunchy salad, sold from open tubs at markets or in cans at corner shops. In the Far East it's often sold fresher and less processed than the canned version found elsewhere in Russia.