1. Preheat the oven to 425 degrees. In a roasting pan, mix the potatoes, diced fennel, carrots, celery, onion and bay leaves with 2 tablespoons of the olive oil, 1/2 teaspoon of the salt and 1/4 teaspoon of the black pepper. Roast, tossing a few times, until tender, about 30 minutes.
2. Lay the halibut over vegetables; drizzle with the white wine. Top fish with remaining olive oil and sprinkle with flour; season with remaining salt and black pepper. Meanwhile, preheat broiler.
3. Move the pan to broiler; broil 6 to 8 minutes, until fish is cooked through.
4. Remove bay leaves. Garnish with fennel fronds and parsley. Serve with the lemon wedges.