- 1 small leek (white and pale green part only), halved and thinly sliced
- 3 garlic cloves, finely chopped
- 1 1/2 teaspoons fennel seeds
- 5 tablespoons extra-virgin olive oil, divided
- 1 medium russet (baking) potato
- 2 medium fennel bulbs, stalks discarded, reserving fronds, and bulb cut into 1/2-inch pieces
- 5 cups water
- 1 (8-inch) length of baguette, cut into 1-inch cubes
- 1/2 cup crème fraîche or sour cream
- 1 teaspoon grated orange zest
- Preheat oven to 375°F with rack in middle.
- Wash leek , then cook with garlic, fennel seeds, and 1 teaspoon salt in 3 tablespoons oil in a heavy medium pot over medium-low heat, stirring occasionally, until softened, about 8 minutes.
- Meanwhile, peel potato and cut into 1/2-inch pieces.
- Add potato, fennel, and water to leek mixture and simmer, covered, stirring occasionally, until vegetables are very tender, 15 to 20 minutes.
- Toss bread cubes with remaining 2 tablespoons oil in a shallow baking pan. Bake, stirring once or twice, until crisp and golden brown, 10 to 15 minutes.
- Purée soup in batches in a blender until smooth (use caution when blending hot liquids). Return to pot and season with salt and pepper.
- Chop 1 tablespoon fennel fronds and whisk together with crème fraîche and zest.
- Serve soup with orange crème fraîche and croutons.