Cut the pickled cucumbers and onions into small cubes and place in a deep bowl so that the herring salad is conveniently mixed.
Chop the boiled eggs into small cubes.
Thoroughly peel the herring fillet of large and small bones and also cut into cubes. Bones need to be given special attention – it is very unpleasant when bones come across in a herring snack. Add the herring to the bowl with the rest of the ingredients.
Add mayonnaise, finely chopped green onions, and stir in the egg, cucumber, and herring salad ingredients.
Combine mustard, French mustard, and olive oil in a deep cup.
Whisk with a fork until smooth, add apple cider vinegar to taste. Salt if necessary, but remember that herring and cucumbers contain salt.
Add dressing to the salad, stir.
Cut out circles or any other interesting geometric shapes for the canapes from slices of rye bread.
Place a tablespoon of fish salad on each sandwich.
Garnish the herring canapes with cranberries and chives.