Place the sliced baby fennel, white wine and fish stock into a pan. Bring to a simmer and cook for 5-7 minutes, or until the fennel is tender. Remove the fennel from the pan using a slotted spoon, set aside and keep warm.
Meanwhile, place the saffron strands into a small bowl with two tablespoons of boiling water and allow to infuse for 5-10 minutes.
Add the saffron and its soaking water to the pan with the fish stock and wine, stirring to combine. Add the turbot to the pan and poach for 1½ minutes on each side. Remove the fish from the pan with a slotted spoon and set aside with the fennel.
Add the cream to the stock mixture and season with salt and freshly ground black pepper. Stir in the butter.
To serve, lay a bed of the fennel slices on a serving plate and place the turbot on top. Pour over the saffron cream sauce and garnish with chopped chives and a sprig of chervil.