Smörgåstårta (Swedish Sandwich Cake)

Name: Smörgåstårta (Swedish Sandwich Cake)
Prep time: 50 min
Total time: 50 min
Cuisine: European
Ingredients: 1 loaf light rye (900g tin) (wholemeal or white, baked in a tin, unsliced & one day old.); 30 g butter (softened); 1 bunch dill (stalks removed & chopped); 85 g smoked salmon (cut into strips); 30 g cream cheese; 25 g crème fraîche; ¼ zest lemon; 1 Tbls lemon juice; 1 tsp horseradish (fresh grated or horseradish sauce); 1 ripe avocado; 1 small handful chives (chopped); 60 g cucumber (peeled, deseeded & chopped); 1 ½ Tbls lemon juice; 280 g whole North Atlantic prawns; ¼ small red onion (very finely chopped); 45 g mayonnaise; 40 g creme fraiche; ¼ zest of lemon; 1 tsp lemon juice; 2 -3 baby cucumbers (finely sliced lengthways); 180 g cream cheese (full fat); a few pea shoots (fresh edible flowers, ie. French marigold petals, pansies and borage)