|Herrings||4 , boned and flattened|
|Onion||1 , cut into thin rings|
Wash the herrings, place skin side down on a board.
Season and roll up from tail end.
Put in Slo cooker.
Place remaining ingredients in a saucepan and bring to the boil.
Transfer to Slo cooker and cook for the recommended time.
Remove the cooking pot and allow the fish to become cold in the liquid.
Chill before serving.