- 2 medium fennel bulbs (sometimes called anise; 1 1/2 lb total), stalks cut off and discarded, and fronds reserved for garnish if desired
- 1 1/2 lb large boiling potatoes
- 3 large garlic cloves, minced
- 1 teaspoon salt
- 1/4 teaspoon black pepper
- 6 tablespoons extra-virgin olive oil
- 2 lb skinless cod fillet (1 inch thick), cut into 6 portions
- Garnish: chopped fennel fronds or fresh flat-leaf parsley
- Accompaniment: lemon wedges
- Special equipment: a Japanese Benriner or other adjustable-blade slicer; a 3-quart shallow baking dish (2 inches deep)
- Preheat oven to 400°F.
- Cut fennel bulbs crosswise into 1/16-inch-thick slices with slicer. Peel potatoes and cut crosswise into 1/16-inch-thick slices with slicer.
- Transfer fennel and potatoes to baking dish and toss with garlic, salt, pepper, and 4 tablespoons oil. Spread vegetables evenly in dish and bake, covered with foil, in middle of oven until just tender, 25 to 30 minutes.
- Season fish with salt and pepper and arrange on top of vegetables. Drizzle with remaining 2 tablespoons oil and bake, uncovered, until fish is just cooked through, 12 to 15 minutes.