Soak the herring in milk or cold tea for an hour if it came out of the barrel rather than a jar. The potatoes must be warm and the herring cold, and that contrast is the entire dish.
It did not make it into the plan for these seven days.
The method above is what decides the dish, not a step-by-step recipe. The link runs a web search on the name: this page has no vetted sources of its own, and will not invent any.