This is the most popular type of herring served at the restaurant Gammel Strand in Copenhagen.
4 pickled herring filets
2 tbsp. sugar
1 tbsp. water
1/2 tbsp. hot curry powder
1/2 cup crème fraîche
6 slices of thin, buttered pumpernickel bread
Sliced red onion
Finely chopped, peeled hard-cooked egg
Sprig of fresh dill
1. Cut herring filets into thirds crosswise, then place in a medium bowl and set aside.
2. Combine sugar and water in a small saucepan, then bring to a boil over medium-high heat. Cool completely.
3. Whisk in hot curry powder and crème fraîche. Pour curry mixture over herring, cover with plastic wrap, and refrigerate for 24 hours. Cover each of the slices of pumpernickel bread with lettuce and 2 pieces of herring. Top with red onion, egg, and a sprig of fresh dill.