Photograph: Maja Smend
In a bowl, mix together the crushed peppercorns with the salt, sugar, 2 tablespoons of the dill and the lemon zest. Remove any pin bones from the fish with clean tweezers.
Put the salmon, skin-side down, on to a large double sheet of kitchen foil. Spread the mixture on top and wrap the fish in the foil, then tightly in clingfilm. Put the salmon upside down on a large dish in the fridge.
Leave the salmon for 2 days and nights, turning it every 8 hours or so and pouring away any excess liquid.
After the 2 days, scrape off and discard the excess marinade mixture.
Sprinkle the remaining dill over the fish and pat it down. If you're not using the salmon straight away, wrap it in clean clingfilm and foil; chill.
To serve, slice it thinly into pieces, on the slant, starting at the tail end.
Tip the plain flour into a bowl and sprinkle over the yeast and sugar, then add 75ml warm water. Mix to make a dough. Cover with clingfilm and leave to double in size – this will take about 20 minutes.
In another bowl, mix the buckwheat (or strong white) flour with the egg yolk, melted butter, warm milk and a big pinch of salt; whisk until smooth.
Add this wet mixture, bit by bit, to the risen dough – use a balloon whisk and beat it to combine. Cover with clingfilm; leave to rise for 30 minutes.
Whisk the egg white in a clean bowl until it forms stiff peaks; fold into the blini mixture.
Wipe a nonstick frying pan with melted butter. Heat; when the butter is sizzling, add ½ tablespoon batter per blini. They will need a minute or so on each side and are ready to turn when bubbles appear on the surface. Transfer to kitchen paper as they are ready; leave to cool.
To serve, put 1 teaspoon of soured cream on each blini and top with gravadlax. Garnish with dill.