Clean and peel the cucumber, cut it in half lengthwise and scrape out the seeds with a tablespoon. Cut cucumber meat into very fine cubes. Mix 2 tablespoons crème fraîche and wasabi. Add the cucumber and season with salt, pepper and sugar.
Wash a lime in hot water, rub dry. Finely grate the peel. Squeeze the juice. Wash the dill, shake dry and chop finely. Mix 3 tablespoons crème fraîche, lime zest, juice and 1/3 of the dill.
Season to taste with salt and pepper. Wash fresh salmon, dab dry. Dice fresh and smoked salmon very finely. Squeeze 1/2 lime. Peel and finely dice shallots. Grind the coriander in the universal chopper.
Set aside some dill, shallots and coriander for garnishing. Mix remaining shallots, dill and coriander, salmon, oil and lime juice. Season to taste with salt and pepper. Put salmon tartar in 4 oiled dessert rings (9 cm Ø) on 4 plates, press lightly, carefully remove dessert rings.
Sprinkle tartar with dill, shallots and coriander. Garnish with lime slices and chervil. Add wasaburgers and lime crème fraîche.