1 With tweezers, remove any small bones from the fish fillets.
2 Rinse fish with cold water and pat dry. Place skin side down in a shallow baking dish.
3 Coarsely crush coriander seeds and peppercorns in a mortar (or use a mini chopper).
4 Squeeze juice from lime. Mix 3 tablespoons of lime juice with crushed spices, salt, sugar, honey and 1 tablespoon oil in a bowl. Evenly sprinkle lime mixture on the fish fillets.
5 Rinse dill, shake dry, pluck fronds and coarsely chop. Sprinkle dill over the fillets. Cover with plastic wrap and refrigerate for 6 hours.
6 About 30 minutes before serving, rinse cucumber and wipe dry. Trim ends, halve cucumber lengthwise and remove the seeds with a spoon.
7 Cut cucumber into small cubes.
8 Peel mango, remove pit and cut into small dice. Peel onion and cut into very thin rings. Mix mango and onion with remaining oil and lime juice and 2-3dashes of Tabasco (or to taste). Season with salt and pepper.
9 Remove dill from marinated fish.
10 Cut fish into thin slices and serve with the salad.