Step 1Line baking sheet with piece of foil large enough to envelope salmon.
Step 2Combine salt, pepper and sugar and spread half of mixture on foil. Place salmon skin-side down on salt mixture. Rub meat side with citrus zest, then cover with remaining salt mixture. Fold aluminum foil over fish and place another sheet pan directly on top. Place weight of some sort--a pan, heavy dish or cans--on top to press salmon to help extract liquid and compact the flesh. Refrigerate 24 hours.
Step 3Remove salmon from marinade, rinse under cold water and pat dry. Slice thinly and serve with toasted brioche as a canape or with greens as a salmon salad.