Preheat the oven to 375 degrees F. Season the fish on both sides with salt, pepper, and Essence.
Saute the fennel and onions in olive oil until golden brown, about 8 minutes. Lay the fish on top, and add the vermouth and fish stock. Cover the pot and bake until the fish is cooked and still tender, 10 to 12 minutes.
Remove from the oven and transfer the fish, fennel, and onion to a platter. Tent to keep warm.
Transfer the cooking juices and the 3 onion rings to a small saucepan. Bring to a boil and cook until reduced by half, about 3 minutes. Add the orange juice and cook until reduced by half again, 3 to 4 minutes. Transfer to a blender, and puree on high speed. Adjust the seasoning, to taste.
Arrange the fish, vegetables and rice on 4 large plates. Drizzle the fish with the orange vinaigrette, garnish with the fennel fronds, and serve.
Yield: 4 servings