Preparation Put oven rack in lower third of oven and preheat oven to 425°F. Cut stalks from fennel bulbs, then chop enough fronds to measure 1/4 cup. Remove any discolored parts from bulbs and quarter bulbs lengthwise, then cut lengthwise into 3/4-inch-thick slices using slicer. Toss fennel with oil, 1/2 teaspoon salt, and 1/4 teaspoon pepper in a 13- by 9-inch (2-quart) glass or ceramic baking dish. Cover tightly with foil and roast 10 minutes, then remove foil and roast 5 minutes more. Meanwhile, rinse fish and pat dry. Sprinkle with remaining 1/4 teaspoon salt and 1/4 teaspoon pepper. Put fish, skin side down, on fennel in baking dish, spooning some of fennel over fish. Return baking dish to oven and roast, uncovered, until fish is opaque and just cooked through, 10 to 12 minutes. Sprinkle fennel fronds over fish and drizzle with olive oil. Serve with orange wedges for squeezing over fish.
Preparation Put oven rack in lower third of oven and preheat oven to 425°F. Cut stalks from fennel bulbs, then chop enough fronds to measure 1/4 cup. Remove any discolored parts from bulbs and quarter bulbs lengthwise, then cut lengthwise into 3/4-inch-thick slices using slicer. Toss fennel with oil, 1/2 teaspoon salt, and 1/4 teaspoon pepper in a 13- by 9-inch (2-quart) glass or ceramic baking dish. Cover tightly with foil and roast 10 minutes, then remove foil and roast 5 minutes more. Meanwhile, rinse fish and pat dry. Sprinkle with remaining 1/4 teaspoon salt and 1/4 teaspoon pepper. Put fish, skin side down, on fennel in baking dish, spooning some of fennel over fish. Return baking dish to oven and roast, uncovered, until fish is opaque and just cooked through, 10 to 12 minutes. Sprinkle fennel fronds over fish and drizzle with olive oil. Serve with orange wedges for squeezing over fish.