Preheat the oven to 200°C/400°F/gas mark 6.
Make an envelope out of foil by folding a large rectangle in half, then securing each side by folding over twice. Repeat to make two envelopes.
Fill each envelope with a fennel bulb, cut in half, 2tbsp olive oil, 1tbsp white wine, a little lemon zest and seasoning. Fold over the top edges then bake in the oven for around 20 minutes, until the fennel is completely tender.
Meanwhile heat a little olive oil in a pan and sear the cod on all sides. Transfer to a baking sheet, season and roast in the oven for 7-10 minutes until the cod flakes and is just cooked through.
Add the beans to a pan of boiling salted water and cook briefly for 3-4 minutes until just tender, but retaining some crunch. Drain and refresh under cold water.
Serve the cod alongside the fennel and beans, pouring over the juices from the baked fennel parcels. Sprinkle with a little lemon juice and chopped chives.