Finely chop the shallot and place the ingredients in a bowl; mix everything together and season with salt, pepper and vinegar.
Take the herring fillets and pat them dry with a piece of kitchen roll. Leave them whole or cut them into suitable pieces.
Spread a little mustard cream on the rye bread, place the herring on top and add more mustard cream so that the herring is covered. Halve the sun-dried eggs and arrange them on top of the herring along with thin slices of onion, capers, chervil, tarragon and crispy buckwheat.
Alternative: If you’re planning a larger lunch where making individual smørrebrød is too time-consuming, the herrings can be cut into smaller pieces, tossed in the mustard cream and served on a platter with bread and accompaniments on the side.
