Combine sugar, salt, and peppercorns in a bowl and mix well. Sprinkle about 1/3 of the mixture over the bottom of a glass baking dish. Place 1 salmon fillet on top, skin-side down. Sprinkle 1/2 the dill on top. Cover with another 1/3 of the sugar mixture. Sprinkle remaining dill on the second fillet and place skin-side up on top of the first fillet. Cover with remaining sugar mixture.

Wrap baking dish tightly in plastic wrap and refrigerate for 18 hours. Turn fillets over and spoon the syrupy liquid over fish before covering again with plastic wrap. Refrigerate another 18 hours.

Rinse fillets lightly in cold water to remove salt. Pat dry. Slice fish thinly at an angle.