In a food processor, combine salt, sugar and juniper berry.
Place the trout fillets, skin side down on a tray covered with saran wrap. Sprinkle the salt and sugar mixture, distribute the dill sprigs. Put another filet on the top and wrap in a saran wrap, place into the tray and another tray on top and then weight down.
Place in the fridge, turn over every 6-8 hours. After 24-36 hours discard dill and wash the trout fillets under cold water and pat dry.
Store in the fridge uncovered for 2-3 hours to air dry until ready to serve.
Serve on pumpernickel bread, ( I served on My New Roots' Life-Changing Loaf of Bread by Sarah Britton I just made into 4 small loaves), fresh young onion (sliced) and dill.