Poach the fish in fish stock and white wine seasoned with salt and pepper, and keep warm.
Put the couscous into a container with the olive oil, chicken stock, salt and black pepper. Cover well with Clingfilm. Allow the couscous to cook for 20 minutes.
Place a ring on the plate (of the kind used to make rice cakes) and use it to mould the couscous. Sprinkle with a little diced peppers and arrange the cooked vegetables around.
Pour over a little white butter and saffron sauce and serve with the fish barely warm.