Using a vegetable peeler, slice the cucumber lengthwise into strips, turning it when you reach the seeds (to avoid them). You should get about 16 slices, some neater than others, but don't worry about that. Cut them in half, season lightly with pepper, and roll them up quite loosely. Pierce each roll with a toothpick to hold it together. Top each with about a 1/2 teaspoon of creme fraiche, 1/8 teaspoon salmon roe, and finally a tiny sprig of dill. Serve.