Defrost the prawns if necessary. Peel up to the tips of the tail. Make a longitudinal incision in the back and remove the dark intestine. Wash the shrimps and pat them dry well.
Clean and wash the fennel, put the green aside. Cut the fennel into thin slices. Peel and finely chop the onions. Heat 1 tablespoon butter in a frying pan. Sauté the fennel and half of the onion cubes.
Add 5-6 tablespoons of water. Steam fennel covered for 8-10 minutes. Season to taste with salt and pepper.
Heat the oil in a pan. Fry the prawns and remaining onion for 2-3 minutes, turning them over. Season with salt and pepper. Remove from the pan, cover and keep warm.
Deglaze the gravy with Pernod and fish stock. Reduce by half over high heat. Cut 150 g butter into small cubes. Gradually stir into the hot, but no longer boiling sauce over a low heat with a whisk until it becomes slightly creamy.
Season to taste. Dress everything. Chop the fennel greens and sprinkle over the top. Serve with a wild rice mixture.