1. To start, let's make the homemade lemon mayonnaise. In a bowl, whisk together 2 large egg yolks, 1 teaspoon of Dijon mustard, and 2 tablespoons of freshly squeezed lemon juice.

2. Gradually add 120 ml (1/2 cup) of oil in a thin stream while continuously whisking until the mixture thickens.

3. Add 1 tablespoon of chopped fresh dill and 1 teaspoon of lemon zest to the mayonnaise, then season with salt and pepper to taste.

4. Next, prepare the rye bread slices by spreading a small amount of butter on each one. You'll need about 4-6 slices of rye bread, depending on their size.

5. Top each bread slice with a lettuce leaf, a slice of cold-smoked salmon, and a slice of peeled crab meat.

6. Peel and slice 2 large eggs and 1 large cucumber. Divide the egg and cucumber slices among the bread slices, placing them on top of the crab meat.

7. Now it's time to assemble the crab cakes. Top each bread slice with a dollop of homemade lemon mayonnaise, followed by a generous helping of crab meat.

8. Garnish each crab cake with a spoonful of fish roe paste and a sprinkle of chopped fresh dill. Serve immediately with lemon wedges on the side.