In a small bowl, whisk together creme fraiche or sour cream, ginger, orange juice, and half the poppy seeds. Season to taste with salt and pepper. Refrigerate until needed.
Peel and julienne carrots. Slice fennel bulb crosswise, as thinly as possible. Cut beans into long strips. Combine vegetables in a medium bowl and toss with dressing immediately before serving. Garnish with remaining poppy seeds.