Smorgastarta

Mix sour cream, lemon zest and juice in a medium bowl. Combine eggs, dill, onion and capers (if using) in another medium bowl. Stir in half of the sour cream mixture.

Add trout, celery, parsley, caraway seeds (if using) and pepper to the remaining sour cream mixture.

To assemble sandwiches: Divide the egg mixture among 4 slices of bread. Top with bread, then spread with the trout mixture. Top with the remaining bread. Cut each sandwich in half and serve.