Salmon Tartare:
Cut the salmon into very small cubes. Mix the salmon and all the other ingredients together in a bowl. Adjust the seasoning of the tartare—especially ensure there is enough salt, pepper, and lemon juice.
Rinse and dry the lettuce leaves. Mix mustard, balsamic, olive oil, salt, pepper, optional lemon juice, and honey/sugar to make a dressing. Adjust the seasoning of the dressing—there should be a little "kick" to it. Toss the lettuce leaves with the dressing.
Rinse and slice the cucumber thinly and place the slices on the plates (see the picture). Arrange the tartare on top of the cucumber and top with lettuce, a spoonful of smoked cheese cream, and the crushed rye bread chips.
Smoked Cheese Cream:
Stir smoked cheese and crème fraîche together and season with salt, pepper, and lemon juice.