Hard boil the eggs: place in a pot with cold water, bring to a boil, remove from heat, and let sit for 10 minutes. Cool in an ice bath, then peel and dice into small pieces.
Pat the pickled cucumber and pearl onions dry with paper towels.
Combine the herring fillet, cucumber, apples, pearl onions, shallots, and hard-boiled eggs in a medium bowl.
Sprinkle the dill over the ingredients and mix gently.
Season with salt, white pepper, and paprika powder to taste.
Fold in mayonnaise until the salad is evenly bound and forms a homogeneous mass.
Cover and refrigerate for 2 hours to allow flavors to blend.