Sweden's national smörgåsbord centerpiece: tender salted herring fillets soaked in a clear sweet 1-2-3 vinegar brine layered with red onion rings, fresh carrot rounds, allspice, and bay leaves.
In a pot, bring vinegar, sugar, and water to a boil until sugar dissolves completely. Remove from heat and chill until completely cold.
Slice desalted herring fillets on a bias into 2cm pieces. Slice red onion and carrot thinly.
In clean glass jars, layer herring pieces alternately with sliced red onion, carrot, allspice, peppercorns, and bay leaves.
Pour chilled pickling brine over herring to submerge. Seal tightly and refrigerate for at least 24 hours (best after 48 hours). Serve cold with rye bread.