- 4 thin pickled herring fillets (about 3/4-pound), cut into 1/2-inch pieces
- 1 small potato, peeled, boiled, cut into 1/4-inch cubes
- 1/4 cup finely chopped onion
- 2 tablespoons finely chopped dill pickle
- 1 small apple, peeled, cored, cut into 1/4-inch cubes
- 2 tablespoons mayonnaise
- Salt and freshly ground black pepper
- 1/2 stick butter, room temperature
- 6 thin slices black bread, halved
- Green leaf lettuce
Place herring pieces, potato, onion, pickle, apple and mayonnaise in a bowl and mix to combine. Add mayonnaise and mix well. Season to taste with salt and pepper.
Spread about 1 teaspoon of butter on each bread half. Top with a lettuce leaf, then with the herring mixture.