Preheat the oven to 200C/400F/Gas 6.
For the sole en papillote, place each sole fillet onto a large sheet of greaseproof paper. Sprinkle over the chopped leeks, drizzle with white wine and dot with butter. Place the lemon slices onto the fish, sprinkle over the chives and season with salt and freshly ground black pepper.
Bring the greaseproof paper up around the fish and seal the edges to make two parcels. Place onto a baking sheet and transfer to the oven to bake for 10-12 minutes, or until the fish is cooked through.
For the vegetables, heat the oil and butter in a pan over a medium heat and fry the carrots and leeks for 2-3 minutes.
Add the coriander seeds and white wine and simmer until reduced slightly.
Add 1-2 tablespoons of water and simmer for another 2-3 minutes, or until the vegetables are tender. Season with salt and freshly ground black pepper, add the herbs and stir to combine.
To serve, place the sole parcels onto plates with the vegetables.
