1. Mix the salt, sugar, the crushed white pepper and the crushed mustard seed (if used).
2. Remove and discard the dill stalks and finely chop the leaves.
3. Cut the salmon filet in 2 pieces of approximately the same length. Put one of the filets (skin side down) in a deep glass dish, cover it with about 3/4 of the sugar/salt mixture. Add the chooped dill.
4. Cover the flesh side of the other fillet with the remaining sugar/salt mixture and place it (skin side up) on top of the one already in the dish.
5. Weight the salmon down and refrigerate for 3-4 days flipping the filets every 12 hours.
6. Slice as thinly as possible at an angle to obtain larger slices. Serve cold by itself or accompanied with bread, fresh cheeses, other cured or raw seafood.
The sugar/salt mixture will extract a considerable amount of water from the salmon. From our experience best results are achieved by keeping the salmon in the liquid for the first 2-3 days. Then drain the liquid and keep in the refrigerator (still with the weight on) for one more day.